Category Archives: 18F14K22

PIC 18F14K22 Microcontroller

1-wire 18F14K22 Accelerometer C i2c LEDs Microcontrollers PIC RS-232

WS2812 RGB and BNO055 IMU PIC Projects

This weekend I spent my Friday afternoon and Saturday at the NW Hobby Expo; talk about an intense desire to get another hobby.

RC Plane NW Hobby Expo

Oh wait… oops; don’t tell me wife 😉 Should be here tomorrow. A little small guy to get me started.

hk_order201602

I was out helping a friend sell 3D printers and interest people into joining our Makerspace.. mission success? I don’t know we’ll see at the next open house.

The makerspace has kept me busy every moment I haven’t been spending with my little man.. thankfully my makerspace activities have been more to my desires.. I developed a little code to run WS2812 LED drivers for a PIC… why we used a PIC (my fav) I’m unsure.. these maker-folks are all Arduino… I borrow a board and took a look. It’s cute.. micros with training wheels. Here is some basic code to generate colors.. maybe it’ll cut your dev time down on a real project.
RGB WS2812 PIC


/*
 * File:   main.c
 * Author: Charles M Ihler
 * Contact at: http://iradan.com
 *
 * Created on Janurary 1, 2015
 *
 * Target Device:
 * 18F14K22 
 *
 * Project: RGB Resistor Clock
 *
 
 * Version:
 * 0.1  Configuration, with reset test
 * 0.2  Send a single color to 1 neopixel (WS2811/WS2812)
 *
 */
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 4000000 //16Mhz FRC internal osc
#define __delay_us(x) _delay((unsigned long)((x)*(_XTAL_FREQ/16000000.0)))
#define __delay_ms(x) _delay((unsigned long)((x)*(_XTAL_FREQ/16000.0)))
#endif

#define CHECK_BIT(var,pos) ((var) & (1<<(pos)))

#include 
#include 
#include 
#include 


//config bits
#pragma config FOSC=IRC, WDTEN=OFF, PWRTEN=OFF, MCLRE=ON, CP0=OFF, CP1=OFF, BOREN=ON
#pragma config STVREN=ON, LVP=OFF, HFOFST=OFF, IESO=OFF, FCMEN=OFF

#define _XTAL_FREQ 64000000 //defined for delay

/*
 * Variables
 */

    int     device_present;             // 1 = 1-wire device on 1-wire bus
    int     i, x, y, temp, an4_value;               //
    long int    decm;
    int     itxdata, txdata;            //int RS232 tx data
    char    rxbuff[10], z[1], buf[4];                 //buffer for T-sense 1-wire device
    float    temperature, f, d;
    volatile unsigned int uart_data;    // use 'volatile' qualifer as this is changed in ISR

/*
 *  Functions
 */

    void interrupt ISR() {

    if (PIR1bits.RCIF)          // see if interrupt caused by incoming data .. unused currently
    {
        uart_data = RCREG;     // read the incoming data
        PIR1bits.RCIF = 0;      // clear interrupt flag
                                //
    }
    // I left this timer interrupt if I needed it later. This is unused.
    if (PIR1bits.TMR1IF)
    {
        //T1CONbits.TMR1ON = 0;
        
        PIR1bits.TMR1IF = 0;
        //T1CONbits.TMR1ON = 1;

    }
}


     void __delay_10ms(unsigned char n)     //__delay functions built-in can't be used for much at this speed... so!
 {
     while (n-- != 0) {
         __delay_ms(10);
     }
 }


void uart_send (unsigned int mydata_byte) {      //bytes

    while(!TXSTAbits.TRMT);    // make sure buffer full bit is high before transmitting
    TXREG = mydata_byte;       // transmit data
}

void write_uart(const char *txt)                //strings
{
                                //this send a string to the TX buffer
                                //one character at a time
       while(*txt)
       uart_send(*txt++);
}

//This code if from Microchip but is unused currently.
void uart_send_hex_ascii(unsigned char display_data)
{

	//unsigned char temp;
	//temp = ((display_data & 0xF0)>>4);
	//if (temp <= 0x09)
	//	Putchar(temp+'0');
	//else
	//	Putchar(temp+'0'+0x07);
        //
	//temp = display_data & 0x0F;
	//if (temp <= 0x09)
	//	Putchar(temp+'0');
	//else
	//	Putchar(temp+'0'+0x07);

	//Putchar('\r');
	//Putchar('\n');
}

void serial_init(void)
{

    // calculate values of SPBRGL and SPBRGH based on the desired baud rate
    //
    // For 8 bit Async mode with BRGH=0: Desired Baud rate = Fosc/64([SPBRGH:SPBRGL]+1)
    // For 8 bit Async mode with BRGH=1: Desired Baud rate = Fosc/16([SPBRGH:SPBRGL]+1)



    TXSTAbits.BRGH=1;       // select low speed Baud Rate (see baud rate calcs below)
    TXSTAbits.TX9=0;        // select 8 data bits
    TXSTAbits.TXEN=1;     // enable transmit
    BAUDCONbits.BRG16=0;

    RCSTAbits.SPEN=1;       // serial port is enabled
    RCSTAbits.RX9=0;        // select 8 data bits
    RCSTAbits.CREN=1;       // receive enabled


    SPBRG=25;               //38,400bps-ish
                            //BRG16=0, 7=31.25k, 25=9.615k

    PIR1bits.RCIF=0;        // make sure receive interrupt flag is clear
    PIE1bits.RCIE=1;        // enable UART Receive interrupt


         __delay_ms(10);        // give time for voltage levels on board to settle

}

void send_low(void){
    LATCbits.LATC0 = 1;
    _delay(5);
    LATCbits.LATC0 = 0;
    _delay(11);
}

void send_high(void){
    LATCbits.LATC0 = 1;
    _delay(11);
    LATCbits.LATC0 = 0;
    _delay(8);
}


void init_io(void) {
    ANSEL = 0x00;         
    ANSELH = 0x00;

    TRISAbits.TRISA0 = 1; // PGD
    TRISAbits.TRISA1 = 1; // PGC
    TRISAbits.TRISA2 = 0; // output
    TRISAbits.TRISA4 = 1; // OSC
    TRISAbits.TRISA5 = 1; // OSC



    TRISBbits.TRISB4 = 0; // output
    TRISBbits.TRISB5 = 1; // input (RX UART)
    TRISBbits.TRISB6 = 0; // output
    TRISBbits.TRISB7 = 0; // output (TX UART)

    LATC = 0x00;

    TRISCbits.TRISC0 = 0; // WG2812 Output
    TRISCbits.TRISC1 = 1; // 
    TRISCbits.TRISC2 = 0; // 
    TRISCbits.TRISC3 = 0; // 
    TRISCbits.TRISC4 = 0; // 
    TRISCbits.TRISC5 = 0; // output
    TRISCbits.TRISC6 = 1; // input
    TRISCbits.TRISC7 = 1; // input

}

void send_black (void) {
        send_low(); //G1
        send_low(); //G2
        send_low(); //G3
        send_low(); //G4
        send_low(); //G5
        send_low(); //G6
        send_low(); //G7
        send_low(); //G8
        
        send_low(); //R1
        send_low(); //R2
        send_low(); //R3
        send_low(); //R4
        send_low(); //R5
        send_low(); //R6
        send_low(); //R7
        send_low(); //R8
        
        send_low(); //B1 00000 0000
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_brown (void) {
        send_low(); //G1 64
        send_low(); //G2 
        send_high(); //G3 
        send_low(); //G4 
        send_low(); //G5 
        send_low(); //G6 
        send_low(); //G7 
        send_low(); //G8 
        
        send_low(); //R1 128
        send_high(); //R2 0
        send_low(); //R3 1
        send_low(); //R4 0
        send_low(); //R5 0
        send_low(); //R6 1
        send_low(); //R7 0
        send_low(); //R8 1      
  
        send_low(); //B1 0
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_orange (void) {
        send_high(); //G1 165 / 1010 0101
        send_low(); //G2 
        send_high(); //G3 
        send_low(); //G4 
        send_low(); //G5 
        send_high(); //G6 
        send_low(); //G7 
        send_high(); //G8 
        
        send_high(); //R1 1111 1111
        send_high(); //R2 
        send_high(); //R3 
        send_high(); //R4 
        send_high(); //R5 
        send_high(); //R6 
        send_high(); //R7 
        send_high(); //R8       
  
        send_low(); //B1 00000 0000
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}


void send_yellow (void) {
        send_high(); //G1 255 / 1111 1111
        send_high(); //G2 
        send_high(); //G3 
        send_high(); //G4 
        send_high(); //G5 
        send_high(); //G6 
        send_high(); //G7 
        send_high(); //G8 
        
        send_high(); //R1 1111 1111
        send_high(); //R2 
        send_high(); //R3 
        send_high(); //R4 
        send_high(); //R5 
        send_high(); //R6 
        send_high(); //R7 
        send_high(); //R8       
  
        send_low(); //B1 00000 0000
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_blue (void) {
        send_low(); //G1
        send_low(); //G2
        send_low(); //G3
        send_low(); //G4
        send_low(); //G5
        send_low(); //G6
        send_low(); //G7
        send_low(); //G8
        
        send_low(); //R1
        send_low(); //R2
        send_low(); //R3
        send_low(); //R4
        send_low(); //R5
        send_low(); //R6
        send_low(); //R7
        send_low(); //R8        
  
        send_high(); //B1
        send_high(); //B2
        send_high(); //B3
        send_high(); //B4
        send_high(); //B5
        send_high(); //B6
        send_high(); //B7
        send_high(); //B8
}

void send_green (void) {
        send_high(); //G1
        send_high(); //G2
        send_high(); //G3
        send_high(); //G4
        send_high(); //G5
        send_high(); //G6
        send_high(); //G7
        send_high(); //G8
        
        send_low(); //R1
        send_low(); //R2
        send_low(); //R3
        send_low(); //R4
        send_low(); //R5
        send_low(); //R6
        send_low(); //R7
        send_low(); //R8        
  
        send_low(); //B1
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_grey (void) {
        send_low(); //G1
        send_low(); //G2
        send_high(); //G3
        send_low(); //G4
        send_low(); //G5
        send_low(); //G6
        send_low(); //G7
        send_low(); //G8
        
        send_low(); //R1
        send_low(); //R2
        send_high(); //R3
        send_low(); //R4
        send_low(); //R5
        send_low(); //R6
        send_low(); //R7
        send_low(); //R8        
  
        send_low(); //B1
        send_low(); //B2
        send_high(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_violet (void) {
        send_low(); //G1
        send_low(); //G2
        send_low(); //G3
        send_low(); //G4
        send_low(); //G5
        send_low(); //G6
        send_low(); //G7
        send_low(); //G8
        
        send_high(); //R1
        send_high(); //R2
        send_high(); //R3
        send_high(); //R4
        send_high(); //R5
        send_high(); //R6
        send_high(); //R7
        send_high(); //R8        
  
        send_high(); //B1
        send_high(); //B2
        send_high(); //B3
        send_high(); //B4
        send_high(); //B5
        send_high(); //B6
        send_high(); //B7
        send_high(); //B8
}

void send_red (void) {
        send_low(); //G1
        send_low(); //G2
        send_low(); //G3
        send_low(); //G4
        send_low(); //G5
        send_low(); //G6
        send_low(); //G7
        send_low(); //G8
        
        send_high(); //R1
        send_high(); //R2
        send_high(); //R3
        send_high(); //R4
        send_high(); //R5
        send_high(); //R6
        send_high(); //R7
        send_high(); //R8        
  
        send_low(); //B1
        send_low(); //B2
        send_low(); //B3
        send_low(); //B4
        send_low(); //B5
        send_low(); //B6
        send_low(); //B7
        send_low(); //B8
}

void send_white (void) {
        send_high(); //G1 255 / 1111 1111
        send_high(); //G2 
        send_high(); //G3 
        send_high(); //G4 
        send_high(); //G5 
        send_high(); //G6 
        send_high(); //G7 
        send_high(); //G8 
        
        send_high(); //R1 1111 1111
        send_high(); //R2 
        send_high(); //R3 
        send_high(); //R4 
        send_high(); //R5 
        send_high(); //R6 
        send_high(); //R7 
        send_high(); //R8       
  
        send_high(); //B1
        send_high(); //B2
        send_high(); //B3
        send_high(); //B4
        send_high(); //B5
        send_high(); //B6
        send_high(); //B7
        send_high(); //B8
}


int main(void) {

    init_io();

    // set up oscillator control register, using internal OSC at 16MHz.
    OSCCONbits.IRCF = 0x07; //set OSCCON IRCF bits to select OSC frequency 16MHz
    OSCCONbits.SCS = 0x00; //set the SCS bits to select internal oscillator block
    OSCTUNEbits.PLLEN = 0x01;   //x4 PLL
    //RCONbits.IPEN = 0;          //disable priority levels

    INTCONbits.PEIE = 1;        // Enable peripheral interrupt
    INTCONbits.GIE = 1;         // enable global interrupt

    temp = 0x10000000;

    while (1) {
        //RGB high bit first
        //if (CHECK_BIT(temp, 0)) {
        //send_high(); //G1    
        //} else {
        //send_low(); //G1    
        //}
        
        send_brown();
        send_orange();
        send_yellow();
        
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);        
        
        send_black();    //1st LED
        send_grey();   //2nd LED
        send_white();     //3rd LED

        
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);    
        
        //send_green();
        //send_violet();
        //send_grey();
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10);
        __delay_ms(10); 
        __delay_us(100);

    }
    return (EXIT_SUCCESS);
}

It’s very very dirty and there is some un-used stuff… but it was a quick hack based on old code and I didn’t optimize the delays at all.
… This is work in progress for a resistor color code clock. I’ll obviously need to switch to a crystal, etc.

I also threw together some basic test code for the 9DOF BNO055 IMU. I bought one just for kicks in case I want to add it to my SRS Pop Can Challenge competition robot. I volunteered for the job left over on our makerspace robot group project… because power systems are a bit of a snooze, and I’m pretty much done, I decided to make my own. It won’t win (because I’m not going for all the points) but it’ll be another robot on the field. Here is some cBode to get you started if you’re interested… I used the Adafruit BOB.. pretty cool and they broke out just enough stuff it seems. I tried it with the UART interface first for kicks.. but then switched to I2C.


/*
 * File:   main.c
 * Author: Charles M Ihler
 * Contact at: http://iradan.com
 *
 * Created on February 8, 2014, 11:39 AM
 *
 * Target Device:
 * 18F14K22 on Tautic 20 pin dev board
 *
 * Project: IMU for PCC
 *
 *
 * Version:
 * 0.1  IO Confoiguration RS232/TX/I2C
 * 0.2  Test BNO055 by UART
 * 0.3  Dump UART interface and get cal status via I2C and send to UART 
 *
 */
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 16000000 //4Mhz FRC internal osc
#define __delay_us(x) _delay((unsigned long)((x)*(_XTAL_FREQ/16000000.0)))
#define __delay_ms(x) _delay((unsigned long)((x)*(_XTAL_FREQ/16000.0)))
#endif

#include 
#include 
#include 
#include 


//config bits
#pragma config FOSC=IRC, WDTEN=OFF, PWRTEN=OFF, MCLRE=ON, CP0=OFF, CP1=OFF, BOREN=ON
#pragma config STVREN=ON, LVP=OFF, HFOFST=OFF, IESO=OFF, FCMEN=OFF

/*
 * Variables
 */

#define r_device_address  0x51 // BNO055 Default Address
#define w_device_address  0x50 // BNO055 Default Address

    unsigned int ACK_bit;
    int i;
    unsigned char byte, tempbyte1, tempbyte2;

    int     w0,w1,w2,w3,w4;     //confirguration words
    int     present;              //device present
    //int     itxdata;            //int RS232 tx data
    //char    buf[10];            //buff for iota
    volatile unsigned int uart_data;    // use 'volatile' qualifer as this is changed in ISR

/*
 *  Functions
 */

    void interrupt ISR() {

    if (PIR1bits.RCIF)          // see if interrupt caused by incoming data
    {
        uart_data = RCREG;     // read the incoming data
        if (uart_data == 0xBB)
        {
            LATAbits.LA0 = 1;
            present = 1;
        }
        PIR1bits.RCIF = 0;      // clear interrupt flag
                                //
    }
    if (INTCONbits.T0IF)
    {
        //LATAbits.LATA0 = 1;
        INTCONbits.T0IF = 0;
    }

}

void __delay_10ms(unsigned char n)     //__delay functions built-in can't be used for much at this speed... so!
 {
     while (n-- != 0) {
         __delay_ms(10);
     }
 }
     
void uart_tx(unsigned int mydata_byte) {
    while(!TXSTAbits.TRMT);    // make sure buffer full bit is high before transmitting
    TXREG = mydata_byte;       // transmit data
}

void write_uart(const char *txt){
    while(*txt != 0) uart_tx(*txt++);     //this send a string to the TX buffer
                                            //one character at a time
}

void serial_init(void)
{

    // calculate values of SPBRGL and SPBRGH based on the desired baud rate
    //
    // For 8 bit Async mode with BRGH=0: Desired Baud rate = Fosc/64([SPBRGH:SPBRGL]+1)
    // For 8 bit Async mode with BRGH=1: Desired Baud rate = Fosc/16([SPBRGH:SPBRGL]+1)



    TXSTAbits.BRGH=1;       // 
    TXSTAbits.TX9=0;        // select 8 data bits
    TXSTAbits.TXEN = 1;     // enable transmit


    RCSTAbits.SPEN=1;       // serial port is enabled
    RCSTAbits.RX9=0;        // select 8 data bits
    RCSTAbits.CREN=1;       // receive enabled

    SPBRG=103;               //

    PIR1bits.RCIF=0;        // make sure receive interrupt flag is clear
    PIE1bits.RCIE=1;        // enable UART Receive interrupt
    INTCONbits.PEIE = 1;    // Enable peripheral interrupt
    INTCONbits.GIE = 1;     // enable global interrupt
    INTCONbits.T0IE = 0;

         __delay_10ms(5);        // give time for voltage levels on board to settle
}


void init_io(void) {
    TRISAbits.TRISA0 = 0; // output
    TRISAbits.TRISA1 = 1; // input
    TRISAbits.TRISA2 = 1; // 
    TRISAbits.TRISA4 = 1; // 
    TRISAbits.TRISA5 = 1; // 
    
    ANSEL = 0x00;         // no A/D
    ANSELH = 0x00;

    TRISBbits.TRISB4 = 1; // RB4 I2C SDA, has to be set as an input
    TRISBbits.TRISB5 = 1; // RB5 = nc
    TRISBbits.TRISB6 = 1; // RB6 I2C SCLK, has to be set as an input
    TRISBbits.TRISB7 = 0; // RS232 TX

    WPUBbits.WPUB4 = 0x01;        //PORT B WEAK PULL UPS
    WPUBbits.WPUB6 = 0x01;
    
    TRISCbits.TRISC0 = 1; // 
    TRISCbits.TRISC1 = 1; // input
    TRISCbits.TRISC2 = 1; // 
    TRISCbits.TRISC3 = 0; // 
    TRISCbits.TRISC4 = 0; // 
    TRISCbits.TRISC5 = 0; // 
    TRISCbits.TRISC6 = 1; // input
    TRISCbits.TRISC7 = 1; // input

    __delay_10ms(10);   //let voltage settle
    
    //write_uart("RESET\n");         // transmit some data

}

void I2C_ACK(void)
{
   PIR1bits.SSPIF=0;          // clear SSP interrupt bit
   SSPCON2bits.ACKDT=0;        // clear the Acknowledge Data Bit - this means we are sending an Acknowledge or 'ACK'
   SSPCON2bits.ACKEN=1;        // set the ACK enable bit to initiate transmission of the ACK bit to the serial eeprom
   while(!PIR1bits.SSPIF);    // Wait for interrupt flag to go high indicating transmission is complete
}

void Send_I2C_Data(unsigned int databyte)
{
    PIR1bits.SSPIF=0;          // clear SSP interrupt bit
    SSPBUF = databyte;              // send databyte
    while(!PIR1bits.SSPIF);    // Wait for interrupt flag to go high indicating transmission is complete
}

unsigned char RX_I2C_Data (void)
{
    RCEN = 1;               // 
    while( RCEN ) continue;
    while( !BF ) continue;
    byte = SSPBUF;
   return byte;
}

void I2C_Control_Write(void)
{
    PIR1bits.SSPIF=0;          // clear SSP interrupt bit
    SSPBUF = w_device_address;             // send the control byte (90 TCN75, EF BMP085)
    while(!PIR1bits.SSPIF)     // Wait for interrupt flag to go high indicating transmission is complete
        {
        i = 1;
          // place to add a breakpoint if needed
        }
    PIR1bits.SSPIF=0;

}

void I2C_Control_Read(void)
{
    PIR1bits.SSPIF=0;          // clear SSP interrupt bit
    SSPBUF = r_device_address;   // send the control byte (90 TCN75, EF BMP085)
    while(!PIR1bits.SSPIF)     // Wait for interrupt flag to go high indicating transmission is complete
        {
        i = 1;
          // place to add a breakpoint if needed
        }
    PIR1bits.SSPIF=0;
   }


void I2C_Start_Bit(void)
{
    PIR1bits.SSPIF=0;          // clear SSP interrupt bit
    SSPCON2bits.SEN=1;          // send start bit
    while(!PIR1bits.SSPIF)    // Wait for the SSPIF bit to go back high before we load the data buffer
        {
        i = 1;
        }
    PIR1bits.SSPIF=0;
}

void I2C_check_idle()
{
    unsigned char byte1; // R/W status: Is a transfer in progress?
    unsigned char byte2; // Lower 5 bits: Acknowledge Sequence, Receive, STOP, Repeated START, START

    do
    {
        byte1 = SSPSTAT & 0x04;
        byte2 = SSPCON2 & 0x1F;
    } while( byte1 | byte2 );
}
/*
 * Send the repeated start message and wait repeated start to finish.
 */
void I2C_restart()
{
    I2C_check_idle();
    RSEN = 1; // Reinitiate start
    while( RSEN ) continue;
}

void I2C_Stop_Bit(void)
{
    PIR1bits.SSPIF=0;          // clear SSP interrupt bit
    SSPCON2bits.PEN=1;          // send stop bit
    while(!PIR1bits.SSPIF)
    {
        i = 1;
        // Wait for interrupt flag to go high indicating transmission is complete
    }
}

void I2C_NAK(void)
{
    PIR1bits.SSPIF=0;           // clear SSP interrupt bit
    SSPCON2bits.ACKDT=1;        // set the Acknowledge Data Bit- this means we are sending a No-Ack or 'NAK'
    SSPCON2bits.ACKEN=1;        // set the ACK enable bit to initiate transmission of the ACK bit to the serial eeprom
    while(!PIR1bits.SSPIF)     // Wait for interrupt flag to go high indicating transmission is complete
    {
        i = 1;
    }
}

void read_imu_status(void){
    
    I2C_Start_Bit();                    // send start bit
    I2C_Control_Write();                // send control byte with read set
    Send_I2C_Data(0x00);                // register

    I2C_restart();                      // restart

    I2C_Control_Read();
    RX_I2C_Data();                      // read high
    tempbyte1=byte;
//    I2C_ACK();                          // ACK
//    RX_I2C_Data();                      // read low
//    tempbyte2=byte;
    I2C_NAK();                          // NAK
    //I2C_restart();
    I2C_Stop_Bit();                     // Send Stop Bit

    uart_tx(tempbyte1);               //send data off raw by UART

}

void read_imu_cal_status(void){
    
    I2C_Start_Bit();                    // send start bit
    I2C_Control_Write();                // send control byte with read set
    Send_I2C_Data(0x35);                // register

    I2C_restart();                      // restart

    I2C_Control_Read();
    RX_I2C_Data();                      // read high
    tempbyte1=byte;
//    I2C_ACK();                          // ACK
//    RX_I2C_Data();                      // read low
//    tempbyte2=byte;
    I2C_NAK();                          // NAK
    //I2C_restart();
    I2C_Stop_Bit();                     // Send Stop Bit

    uart_tx(tempbyte1);               //send data off raw by UART

}

void write_imu_9DOF(void)
{

    I2C_Start_Bit();                    // send start bit
    I2C_Control_Write();                // send control byte
    Send_I2C_Data(0x3D);                // address
    Send_I2C_Data(0x1C);                // enable 9dof
    I2C_Stop_Bit();

}

void i2c_muck(void)
{

    I2C_Start_Bit();                     // send start bit
    I2C_Control_Write();                  // send control byte with read set

    //if (!SSP1CON2bits.ACKSTAT)
    //LATCbits.LATC1 = 0;                   //device /ACked?

    Send_I2C_Data(0x01);                //pointer
    Send_I2C_Data(0xE1);                //1 shot, 12bit res
    I2C_Stop_Bit();

    __delay_10ms(50);                     //wait for conversion

    I2C_Start_Bit();                     // send start bit
    I2C_Control_Write();                  // send control byte with read set

    //    if (!SSP1CON2bits.ACKSTAT)
//    LATCbits.LATC1 = 0;

    Send_I2C_Data(0x00);                //pointer

    I2C_restart();                      //restart
    I2C_Control_Read();
    RX_I2C_Data();                      //read high
    tempbyte1=byte;
    I2C_ACK();                          //ACK
    RX_I2C_Data();                      //read low
    tempbyte2=byte;
    I2C_NAK();                          //NAK
    //I2C_restart();
    I2C_Stop_Bit();                     // Send Stop Bit

    uart_tx(tempbyte1);               //send data off raw by UART
    uart_tx(tempbyte2);
}


int main(void) {

    // set up oscillator control register, using internal OSC at 16MHz.
    OSCCONbits.IRCF = 0x07; //set OSCCON IRCF bits to select OSC frequency 16MHz
    OSCCONbits.SCS = 0x02; //set the SCS bits to select internal oscillator block
    //OSCTUNEbits.PLLEN = 0x01;   // PLL ENABLE FOSC -> 64MHz
    //OSCTUNEbits.TUN = 0x63;     ///trim up that frequency to get closed to 115200

    init_io();
    serial_init();
  
    SSPCON1bits.SSPM=0x08;       // I2C Master mode, clock = Fosc/(4 * (SSPADD+1))
    SSPCON1bits.SSPEN=1;         // enable MSSP port
    SSPADD = 0x09;             // 100KHz

    // ***********************************************************************************
    __delay_10ms(100);

    
    //init -- check and wait for IMU
    
    // test
    tempbyte1 = 0xFF;
    
    uart_tx(tempbyte1);               //send data off raw by UART
    uart_tx(0xAA);
    
    __delay_10ms(100);
    
    read_imu_status();    
    //set IMU for 9DOF
    __delay_10ms(10);
    
    
    write_imu_9DOF();
    
    //     UART method
    //     uart_tx(0xAA);                   //Start
    //     uart_tx(0x00);                   //read
    //     uart_tx(0x3D);                   //address 
    //     uart_tx(0x01);                   //length 
    //     uart_tx(0x1C);                   //data 9DOF

    __delay_10ms(50);

    while (1) {
         __delay_10ms(10);                   //delay for debugging

        LATAbits.LA0 = 0;           //good rx flag off
        //LATCbits.LATC3 = 0;
        //__delay_ms(149);
        //LATCbits.LATC3 = 1;     //debugging
        read_imu_cal_status();
  
        LATAbits.LA0 = 1;           //good rx flag on
         __delay_10ms(150);                   //delay for debugging
        
     }                                      //... wash, rinse, repeat
    return;
}



So yeah, again also sloppy but maybe you can use some of it. Price is right anyways.

Okay well maybe you might have notices a TINY gap in posting… it seems I greatly underestimated the amount of time a baby consumes in your life. I have a 9 month old son now.. he is running around trying to chew on USB cables (his favorite)… he’s just now realizing a bit of independence and with a recent purchase of a nice Lenovo Yoga 900 to replace my couple month old dead Sony Vaio I now can develop from the couch.. though I have a porta-crib in the workshop 🙂

1-wire 18F14K22 C Electronics Interface Microcontrollers PIC Weather

iButtonLink T-Sense 1-wire sensor (Maxim DS18B20) + PIC 18F14K22

I came across a stash of iButton T-sense 1-wire sensors.. so I grabbed a couple and decided to check out 1-wire.

Maxim makes a 1-wire device called the DS18B20. It’s a 9-12 bit temperature sensor with the possibility of being powered by parasitic power from the data line. This cuts the signal path down to a single DQ line and a return. A company called iButtonLink produces a nice little wrapper around this device called a T-Sense. There are a couple pieces of software out there that will allow you to hook these up to monitoring systems, I don’t have any though. These devices come with a 64-bit address code and can be daisy-chained which makes having many of these devices monitored very nice.

At first I thought, ugh.. lame I have to send, and parse 64-bit codes in a little 8 bit micro.. doesn’t sound like a ton of fun for just fooling around on a day off.. thank fully they have a “Skip ROM” feature/command which works similar to a broadcast but can only be used when you have one device on the bus. If there is one thing left in this project I might consider finishing it’d be to add the addressing in and daisy-chain a few of these.

Most of my research came from Microchip’s Application Note AN1199 though the T-Sense Users Manual also helped out including determining the wiring diagram.

For my circuit I hooked up 5VDC (but later ran it on 3.3V just fine) and the 5VDC return on pins 1 & 2. Then the DQ link and return on pins 4&5. The signaling is interesting as the 1-wire bus needs a weak pull and works with an open collector circuits. The master starts all signaling, writes and reads. The 1’s and 0’s are based on how long the master or slave sinks the DQ line. To accomplish this in the PIC microcontroller I switched the port from an output to a three state input when I needed the port to be in weak-pull up mode (which is also hand when I need to sample the port for a response from a slave). The pull up on the resistor in my circuit is 10Kohm but I’ve seen 4.7KOhm and I’m sure anywhere in the neighborhood is fine. Finally if you do some digging you’ll notice I run this in low speed mode, if I remember correctly the “high speed” mode is 4x faster. I don’t think speed of data transfer is really relevant when you’re waiting for 750ms for a temperature conversation though.

T-sense sensor and 18F14k22 PIC Microcontroller on the breadboard
T-sense sensor and 18F14k22 PIC Microcontroller on the breadboard

I initially started with just determining if there was a 1-wire device on the bus. If you perform a “reset” (master sinks the bus low for 480us then releases to hi-z for 70us and then performed a sample.. any (all) device(s) will sink the line slow to prove their presence…then another 410us of delay before continuing. I got this one first try.. better luck than my first time with I2C! I then wrote the code (including sampling tidbits of Microchip AN1199 code to optimize) to do an actual temperature conversion and request it (by commanding a “read scratch pad”). The device dumps all 9 bytes of it’s registers. On that note I just remembered I should mention I did NOTHING with the CRC byte.. that’s all you if you care.

My temperature conversion code looks like this: (bus control m = master or PIC, s=slave or sensor)

m RESET

s PRESENCE flag

m SKIP ROM (0xCC)

m CONV TEMP (0x44)

m HOLD DQ (Hold line high 750ms for 12bit conversion .. I am guessing we hold it high for the parasitic power supply)

m RESET

s PRESENCE flag

m SKIP ROM (0xCC)

m READ SCRATCHPAD (0xBE)

s 9 Bytes of Data

and that looks like…

1-wire data capture on the logic analyzer
1-wire data capture on the logic analyzer

 

The 12-bit conversion is basically 0.0625 deg C for every bit from 0C, The LSB holds a temperature sign.

The output of my program looks like..

Final Results!
Final Results!

There are tons of details on what a “1” is an what a “0” is, the ROM code (READ ROM, MATCH ROM), changing the configuration to 9bit for 94 ms conversions over 12bit 750ms conversions. This is all stuff you can grab out of the DS18B20 specification sheet or AN1199.

I hope you get some use out of this.. I still have enough of these T-Sense modules.. maybe if someone really wants one I’ll drop it in the mail… or perhaps we can set up a big box of electronics to ship around and I can dump some in there.

Items I used to make this happen:

TAUTIC 20-pin Development Board

Microchip PIC 18F14K22

AST Breadboard Buddy Pro

AST tinyLEDx4

iButtonLink T-Sense

CAT5 breakout board (eBay?)

Microchip PICKit 3

Then miscellaneous tools, test equipment, jumpers and a breadboard.

 

The good stuff (my code):

.. also found here on pastebin: http://pastebin.com/HrLg1GqL

 


/*
 * File:   main.c
 * Author: Charles M Douvier
 * Contact at: http://iradan.com
 *
 * Created on Janurary 1, 2015
 *
 * Target Device:
 * 18F14K22 on Tautic 20 pin dev board
 *
 * Project: Maxim 1-Wire Testing
 *
 * Details of 1-wire protocol using Microchip AN1199
 * Field device http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf
 * The 1-Wire Protocol is registered trade mark of Dallas/Maxim semiconductor.
 *
 * Some code was use by the AN1199 App Note Source code; I got stuck looking for a fast way of txing by bit-bang (yes never did this before)
 * The agreement below mentions a license agreement accompaning this software; There was none. I'll note where this software was used if you
 * want to re-write without the Microchip bits.
 * The Microchip licensing as follows:
 *
 *  * FileName:        1wire.c
 * Dependencies:
 * Processor:       PIC18
 * Complier:        MCC18 v3.13
 * Company:         Microchip Technology, Inc.
 *
 * Software License Agreement
 *
 * Copyright © 2004-2007 Microchip Technology Inc.  All rights reserved.
 *
 * Microchip licenses to you the right to use, copy and distribute Software
 * only when embedded on a Microchip microcontroller or digital signal
 * controller and used with a Microchip radio frequency transceiver, which
 * are integrated into your product or third party product (pursuant to the
 * sublicense terms in the accompanying license agreement).  You may NOT
 * modify or create derivative works of the Software.
 *
 *
 * You should refer to the license agreement accompanying this Software for
 * additional information regarding your rights and obligations.
 *
 * SOFTWARE AND DOCUMENTATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY
 * KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION, ANY WARRANTY
 * OF MERCHANTABILITY, TITLE, NON-INFRINGEMENT AND FITNESS FOR A PARTICULAR
 * PURPOSE. IN NO EVENT SHALL MICROCHIP OR ITS LICENSORS BE LIABLE OR OBLIGATED
 * UNDER CONTRACT, NEGLIGENCE, STRICT LIABILITY, CONTRIBUTION, BREACH OF
 * WARRANTY, OR OTHER LEGAL EQUITABLE THEORY ANY DIRECT OR INDIRECT DAMAGES OR
 * EXPENSES INCLUDING BUT NOT LIMITED TO ANY INCIDENTAL, SPECIAL, INDIRECT,
 * PUNITIVE OR CONSEQUENTIAL DAMAGES, LOST PROFITS OR LOST DATA, COST OF
 * PROCUREMENT OF SUBSTITUTE GOODS, TECHNOLOGY, SERVICES, OR ANY CLAIMS BY
 * THIRD PARTIES (INCLUDING BUT NOT LIMITED TO ANY DEFENSE THEREOF), OR OTHER
 * SIMILAR COSTS.
 *
 *
 *
 * Version:
 * 0.1  Configuration, with reset test
 * 0.2
 *
 */
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 16000000 //4Mhz FRC internal osc
#define __delay_us(x) _delay((unsigned long)((x)*(_XTAL_FREQ/4000000.0)))
#define __delay_ms(x) _delay((unsigned long)((x)*(_XTAL_FREQ/4000.0)))
#endif

#include 
#include 
#include 
#include 


//config bits
#pragma config FOSC=IRC, WDTEN=OFF, PWRTEN=OFF, MCLRE=ON, CP0=OFF, CP1=OFF, BOREN=ON
#pragma config STVREN=ON, LVP=OFF, HFOFST=OFF, IESO=OFF, FCMEN=OFF

#define _XTAL_FREQ 16000000 //defined for delay

/*
 * Variables
 */

    int     device_present;             // 1 = 1-wire device on 1-wire bus
    int     i, x, y, int_temp, an4_value;               //
    long int    decm;
    int     itxdata, txdata;            //int RS232 tx data
    char    rxbuff[10], z[1], buf[4];                 //buffer for T-sense 1-wire device
    float    temperature, f, d;
    volatile unsigned int uart_data;    // use 'volatile' qualifer as this is changed in ISR

/*
 *  Functions
 */

    void interrupt ISR() {

    if (PIR1bits.RCIF)          // see if interrupt caused by incoming data .. unused currently
    {
        uart_data = RCREG;     // read the incoming data
        PIR1bits.RCIF = 0;      // clear interrupt flag
                                //
    }
    // I left this timer interrupt if I needed it later. This is unused.
    if (PIR1bits.TMR1IF)
    {
        //T1CONbits.TMR1ON = 0;
        PIR1bits.TMR1IF = 0;
        //T1CONbits.TMR1ON = 1;

    }
}


     void __delay_10ms(unsigned char n)     //__delay functions built-in can't be used for much at this speed... so!
 {
     while (n-- != 0) {
         __delay_ms(10);
     }
 }


void uart_send (unsigned int mydata_byte) {      //bytes

    while(!TXSTAbits.TRMT);    // make sure buffer full bit is high before transmitting
    TXREG = mydata_byte;       // transmit data
}

void write_uart(const char *txt)                //strings
{
                                //this send a string to the TX buffer
                                //one character at a time
       while(*txt)
       uart_send(*txt++);
}

//This code if from Microchip but is unused currently.
void uart_send_hex_ascii(unsigned char display_data)
{

	//unsigned char temp;
	//temp = ((display_data & 0xF0)>>4);
	//if (temp <= 0x09)
	//	Putchar(temp+'0');
	//else
	//	Putchar(temp+'0'+0x07);
        //
	//temp = display_data & 0x0F;
	//if (temp <= 0x09)
	//	Putchar(temp+'0');
	//else
	//	Putchar(temp+'0'+0x07);

	//Putchar('\r');
	//Putchar('\n');
}

void serial_init(void)
{

    // calculate values of SPBRGL and SPBRGH based on the desired baud rate
    //
    // For 8 bit Async mode with BRGH=0: Desired Baud rate = Fosc/64([SPBRGH:SPBRGL]+1)
    // For 8 bit Async mode with BRGH=1: Desired Baud rate = Fosc/16([SPBRGH:SPBRGL]+1)



    TXSTAbits.BRGH=1;       // select low speed Baud Rate (see baud rate calcs below)
    TXSTAbits.TX9=0;        // select 8 data bits
    TXSTAbits.TXEN=1;     // enable transmit
    BAUDCONbits.BRG16=0;

    RCSTAbits.SPEN=1;       // serial port is enabled
    RCSTAbits.RX9=0;        // select 8 data bits
    RCSTAbits.CREN=1;       // receive enabled


    SPBRG=25;               //38,400bps-ish
                            //BRG16=0, 7=31.25k, 25=9.615k

    PIR1bits.RCIF=0;        // make sure receive interrupt flag is clear
    PIE1bits.RCIE=1;        // enable UART Receive interrupt


         __delay_ms(10);        // give time for voltage levels on board to settle

}


void init_io(void) {
    ANSEL = 0x00;         
    ANSELH = 0x00;

    TRISAbits.TRISA0 = 0; // output
    TRISAbits.TRISA1 = 0; // output
    TRISAbits.TRISA2 = 0; // output
    TRISAbits.TRISA4 = 0; // output
    TRISAbits.TRISA5 = 0; // output



    TRISBbits.TRISB4 = 0; // output
    TRISBbits.TRISB5 = 1; // input (RX UART)
    TRISBbits.TRISB6 = 0; // output
    TRISBbits.TRISB7 = 0; // output (TX UART)

    LATC = 0x00;

    TRISCbits.TRISC0 = 1; // AN4
    TRISCbits.TRISC1 = 1; // 1-wire data
    TRISCbits.TRISC2 = 0; // 
    TRISCbits.TRISC3 = 0; // 
    TRISCbits.TRISC4 = 0; // 
    TRISCbits.TRISC5 = 0; // output
    TRISCbits.TRISC6 = 1; // input
    TRISCbits.TRISC7 = 1; // input

}


void init_adc (void)
{
    ANSELbits.ANSEL4=1;         //PORTC.0
    ADCON2bits.ADCS = 0x02;     //Fosc/32
    ADCON2bits.ADFM=0;          //left oriented
    ADCON1=0x00;
}

void read_adc (void)
{
    ADCON0bits.CHS0 = 0;        // AD4
    ADCON0bits.CHS1 = 0;
    ADCON0bits.CHS2 = 1;
    ADCON0bits.CHS3 = 0;
    ADCON0bits.ADON = 1;        // A/D ON
    __delay_us(5);

    ADCON0bits.GO   = 1;        // ..GO!

    __delay_us(5);

        while (ADCON0bits.GO) continue;              //wait for conversion
        an4_value = ADRESH;                          //AN4 value
}

void one_wire_reset(void) {
    device_present = 0x00;
    TRISCbits.TRISC1 = 0;
    LATCbits.LATC1 = 0;
    __delay_us(240);        //delay 480 us
    __delay_us(240);
    TRISCbits.TRISC1 = 1;
    __delay_us(70);
    if (!PORTCbits.RC1) {
            device_present = 0x01;
    }
    __delay_us(205);        //delay 410 us
    __delay_us(205);
}

//this looks a lot like the Microchip code, it was not I just happened to be on the right track.
void one_wire_tx_bit(unsigned char txbit) {         // write a bit
    if (txbit) {
    TRISCbits.TRISC1 = 0;
    LATCbits.LATC1 = 0;
    __delay_us(6);    
    TRISCbits.TRISC1 = 1;
    __delay_us(64);      
    }
    else {      
    TRISCbits.TRISC1 = 0;
    LATCbits.LATC1 = 0;
    __delay_us(60);    
    TRISCbits.TRISC1 = 1;
    __delay_us(10);    
    }
}

//from Microchip AN1199 code, renamed and slightly modified to match my software
/**********************************************************************
* Function:        void OW_write_byte (unsigned char write_data)
* PreCondition:    None
* Input:		   Send byte to 1-wire slave device
* Output:		   None
* Overview:		   This function used to transmit a complete byte to slave device.
*				   
***********************************************************************/
void one_wire_tx_byte (unsigned char write_data)
{
	unsigned char loop;
	
	for (loop = 0; loop < 8; loop++) 	{ 		one_wire_tx_bit(write_data & 0x01); 	//Sending LS-bit first 		write_data >>= 1;					// shift the data byte for the next bit to send
	}	
}	


//from Microchip AN1199 code: I gathered the essence of this but seeing as I am not using most of the AN1199 code
//and this would not work with XC8 I had to re-write this.
/**********************************************************************
* Function:        unsigned char OW_read_bit (void)
* PreCondition:    None
* Input:		   None
* Output:		   Return the status of the OW PIN
* Overview:		   This function used to read a single bit from the slave device.
*				   
***********************************************************************/

unsigned char one_wire_rx_bit (void)
{
	unsigned char read_data; 
        read_data = 0x00;
	//reading a bit 
	TRISCbits.TRISC1 = 0;
        LATCbits.LATC1 = 0; 						// Drive the bus low
	__delay_us(6);						// delay 6 microsecond (us)
	TRISCbits.TRISC1 = 1;  						// Release the bus
	__delay_us(9);						// delay 9 microsecond (us)

        if (PORTCbits.RC1) {                                    //read 1 or 0
            read_data = 0x01;
        }

	__delay_us(55);						// delay 55 microsecond (us)	
	return read_data;
}


/**********************************************************************
* Function:        unsigned char OW_read_byte (void)
* PreCondition:    None
* Input:		   None
* Output:		   Return the read byte from slave device
* Overview:		   This function used to read a complete byte from the slave device.
*				   
***********************************************************************/

unsigned char one_wire_rx_byte (void)
{
	unsigned char loop, result=0;
	
	for (loop = 0; loop < 8; loop++)                // here we are reading 8 bits (1 byte) 	{ 		 		result >>= 1; 				// shift the result to get it ready for the next bit to receive
		if (one_wire_rx_bit())
		result |= 0x80;				// if result is one, then set MS-bit
	}
	return result;					
}	

void one_wire_conversion_pulse(void) {
    	TRISCbits.TRISC1 = 0;
        LATCbits.LATC1 = 1; 		 //For T conv we drive the DQ line high for 750ms (12bit)
	__delay_us(250);                 // delay 
	__delay_us(250);                  
        __delay_us(250);                  
	TRISCbits.TRISC1 = 1; 
        LATCbits.LATC1 = 0;             //just in case this causes problems elsewhere                              
}

int main(void) {

    init_io();

    // set up oscillator control register, using internal OSC at 16MHz.
    OSCCONbits.IRCF = 0x07; //set OSCCON IRCF bits to select OSC frequency 16MHz
    OSCCONbits.SCS = 0x02; //set the SCS bits to select internal oscillator block

    //RCONbits.IPEN = 0;          //dsiable priority levels

    INTCONbits.PEIE = 1;        // Enable peripheral interrupt
    INTCONbits.GIE = 1;         // enable global interrupt


    init_adc();                 //unused but AN4 is there if I need it
    serial_init();

    uart_send ('x');

        LATAbits.LATA0 = 0; //this is just for debugging with an LA..
        __delay_us(1);
        LATAbits.LATA0 = 1; //also confirms oscillator setup is correct.. 1us width
        __delay_us(1);
        LATAbits.LATA0 = 0;

    while (1) {

        one_wire_reset();

        if (device_present) {
            LATCbits.LATC2 = 1;             //this is a 1-wire device out there for debugging

            one_wire_tx_byte(0xCC);         //skip-rom (similar to a broadcast)

            one_wire_tx_byte(0x44);         //do a temp conversion

            one_wire_conversion_pulse();    // hold DQ line high for 750ms

            one_wire_reset();

            //add additional check here later

            one_wire_tx_byte(0xCC);         //skip-rom (similar to a broadcast)

            one_wire_tx_byte(0xBE);         //read scratch pad

            for(i = 0; i<9; i++)            //reading all 9 bytes on the T-Sense
   		rxbuff[i] = one_wire_rx_byte();
            // T-Sense
            //  Byte 0 LSB of Temp
            //  Byte 1 MSB of Temp and sign

            // LSB
            //  2^3 2^2 2^1 2^0 2^-1 2^-2 2^-3 s^-4
            // MSB
            // S S S S S 2^6 2^5 2 ^ 4



            temperature = 0;
            f = 0.0625;

            //z[0] = rxbuff[1];
            //x = atoi(z);
            x = rxbuff[1];

            if (x & 0b10000000) {
                uart_send('-');
            } else {
                uart_send('+');
            }
            
            x = x & 0b00000111;

            int_temp = 0;

            int_temp = rxbuff[0];

            if (x & 0b00000001)
                int_temp = int_temp + 0x100;
            if (x & 0b00000010)
                int_temp = int_temp + 0x200;
            if (x & 0b00000100)
                int_temp = int_temp + 0x400;

            temperature = int_temp * f;
            
            int_temp = temperature;

            itoa(z, int_temp, 10);
            write_uart(z);
            uart_send('.');

            d = temperature - int_temp;

            decm = d * 1000;

            //page 374 of XC8 user guide
            ltoa(buf,decm,10);  //long conversion to buffer
            y=strlen(buf);  //uh, adding leading zeros..
            y=3-y;      //probably a better way of doing thing
            while (y)       //first figure out how many zeros
            {
                uart_send('0');  //missed 3-string length
                y=y-1;  //then send them until done
            }   
            write_uart (buf);
        
            uart_send(0x0A);        //LF
            uart_send(0x0D);        //CR

            //temperature   float temperature
            //int_temp      interger value of temperature

            __delay_10ms(254);
        }

    }
    return (EXIT_SUCCESS);
}

 

 

 

 

 

 

18F14K22 Accelerometer Analog to Digital Converter C Electronics Microcontrollers Motors PIC Steppers

18F14K22 Self-Balancing Platform

Well, it’s not finished but this is what I’m working on:

Balancing platform on a breadboard
Balancing platform on a breadboard

Ta-da.. yet another balancing something-or-rather.. except this one isn’t so great at it’s balance. This was a big old fail. I went wrong with steppers… I should have just used DC motors and maybe the next version I will. I used Pololu A4988 stepper motor drivers (A4988-based)  to control my steppers while attempting to use variable speed step resolution control. This worked okay but really while trying to drop holding current while balanced was a nightmare. Also the current usage was above what I consider useful… either backing the current limiting off to save some power (and your driver) then loosing control or you’re just cooking your motor driver and the current isn’t useful other than for a cute demonstration or a non-battery powered application.

I’m not dropping code, you can request it directly if you want it but it’s nothing magical. It has my own hacked up version of a PID loop. I didn’t use derivative. I think far too many cycles are wasted on it when PI will probably work for you. I haven’t fine tuned it because I’m unhappy with my results.

I was a little bummed out on past-Chas’ selection of an MMA7361 accelerometer;  I had gotten it from Sparkfun who-knows-how-long-ago. The link leads to the retired product. It’s just plain voltage output per axis. I must have still been shying away from I2C at the point? The board shown below:

Accelerometer break-out board
Accelerometer break-out board

For a micro I used a PIC 18F14K22 on the TAUTIC dev board with some AtomSoft breadboard goodies for troubleshooting, power and the serial interface (Breadboard Buddy).  <– that link will probably die soon. Tindie updates a lot and products are replaced with newer versions.. if you sniff around you’ll find it.

I’ll move along to another project now, perhaps order some parts and revisit this one again. If you run along this and you’ve done this with steppers I’d be interested in knowing how it worked out for you.