I took a hiatus from blogging for a few years. I decided it’d be clever to start a makerspace. https://snocomakers.org … yeah it worked out but wow I really have to recommend avoiding any part of running a makerspace if you want to have time to do anything else, at all. I didn’t do any lawn work in 2018.. that did not make the wife happy.
In late 2018 I claimed makerspace success. It was a proper makerspace with all the required tools and more and was the largest organization in the state. I decided it was time to step down and let some other folks shape it. So.. I guess, here I am again? I’ll probably drop my hot tips and tricks for starting up a makerspace in a couple weeks.
So on to this missing content business: Short-story-long, I created a cloudy service for access control on doors & equipment which I thought I’d monetize but decided against… however while creating it I moved my hosting package over to an upgraded account. Somehow in the process I lost my backup of this blog… ARG! The last one I had was from late 2014. I know I had a newer one but the backups were on my dead Yoga. So… sorry for all that good stuff missing… oh well. I will probably drop all my code for the cloudy based access control system in the future. It’s in php server side and python on a rpi zero at the reader… nice and cheap. p.s. I dislike Python. It was my first python project, it’ll be my last. Kudos to you if you’re a fan… I think you’re <TAB>insane.
If you showed up here on a 404 and hope to score something I had before I did capture all my media in an FTP upload.. let me know what you’re looking for and I’ll hook you up.
I sat at the bench this morning waiting for the inspiration to continue on with a project I’m working on with Francesco; I gave in to procrastination.
I wrote some assembler code to generate WWVB signal from a PIC a few months ago, remember? That stirred some interest from overseas folks looking for a way for their automatically update their “atomic” watches… apparently there isn’t some NTP device or anything else easily found to be purchased to do this. I was asked to do this NTP, but I’ll leave that for someone with a ‘Pi–I gave mine away to a kid. I did this project using GPS and a PIC micro.
It’s a pretty simple setup, gobble up a GPRMC sentence, pick off the data I need and spit out time. I generate 60KHz with the PWM module within the PIC (okay it’s 62KHz, but that should be close enough).. switch it through a 4066 to generate my time code.
GPRMC: there are other sentences you can use, but my cheapo module only spits out 4 sentences and GPRMC is the only one with time and date, so it’ll do. I re-used my GPGGA parsing code.. there is probably some left-overs in there if you look at the code below. I also dump the working string (first 63 bits of GPGGA) followed by the day number of the year which is calculated on the the UART, pick it up off the TX line @ 9,600 baud.. It’s spits it out about once a minute (in between time transmissions). I ended up using some DOY code online because I found some nice code that included determining if it was a leap year for day-of-year determination; I left the URL in the code.
The code isn’t finished nor is it accurate: it doesn’t recognize the valid data bit yet, and just spits out time whenever it feels like it so the time can be off by up to 59 seconds. I’ll work on this later on since I was just looking for proof of concept so I could get the hardware going and off a breadboard. I built up the circuit in eagle.. I’ll check it a few more times and have a couple PCBs made for round one of testing. The prototype was built on a Tautic 18F26K22 dev board, I considered just having the dev board plug-in but that’s probably a waste of $$.
You’ll note the SMA jack, perhaps this is over kill since I’ll never have a good enough antenna to match 60KHz… I don’t really know what to do with that yet, wire antenna for now I suppose. (version 2?) It’s likely illegal to sell these since it’s purposefully broadcasting, fat chance I’m doing the research beyond the FCC. I’ll look it up tomorrow but I suspect Part 15 doesn’t apply to 60KHz.
Version 1 of the GPS>WWVB board
The code is a total hack job.. poorly documented, perhaps even incorrectly documented. I know I have “place-holder” functions.. but like I said.. it was a start to get my time code and it was close enough for testing; you get what you pay for! 🙂
/*
* File: main.c
* Author: Charles M Douvier
* Contact at: http://iradan.com / 0xEE.net / @chasxmd
* Created on April 4th, 2014
*
* Target Device: 18F26K22
*
* Project: GPS --> WWVB simulator
*
* This version uses the GPRMC block
* This is a limitation because GPRMC doesn't pass seconds
* The time passed will always be up to 60 seconds off
* I have to deterine DDMMYY --> Day of year, year
* No simple leap year info in GPS :(
*
* TODO
* Determine GPS lock and output to LED
* Consider re-writing how I am writing my time code
*
* I'll re-write this sometime with a better (more expensive) GPS module.
*
* Version:
* 0.1 First build I could prove I had GPS lock
* 0.2 Output time/date on 232
*
*/
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 8000000 //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=INTIO67, WDTEN=OFF, PWRTEN=OFF, CP0=OFF, CP1=OFF, BOREN=ON
#pragma config STVREN=ON, LVP=OFF, HFOFST=OFF, IESO=OFF, FCMEN=OFF
//WRT=OFF, FOSC=INTOSC, MCLRE=ON
#define _XTAL_FREQ 8000000 //defined for delay
char ctxt[120], wstr[120]; //buff NMEA string, working string
char str1[20], str2[20], c, latstr, lonstr, setstr, doych[8];
char hourch[3], minch[3], secch[3], daych[3], monthch[3], yearch[3];
char buffer[32] = "none"; //temp dump
volatile unsigned int ping, isrcall, index, reading, new_rx;
int ready, gpgga, gprmc, mode; //gps associated vars
int leap_year, dayint, monthint, yearint, year4int, secondint, minuteint, hourint;
long doy;
int min_40, min_20, min_10, min_8, min_4, min_2, min_1;
int hour_20, hour_10, hour_8, hour_4, hour_2, hour_1;
int doy_200, doy_100, doy_80, doy_40, doy_20, doy_10;
int doy_8, doy_4, doy_2, doy_1, leapint;
int year_80, year_40, year_20, year_10, year_8, year_4, year_2, year_1;
//char *rxdata;
//volatile unsigned int uart_data; // use 'volatile' qualifer as this is changed in ISR
/*
* Interrupt Service
*/
void interrupt ISR() {
if (PIR1bits.RCIF){ // see if interrupt caused by incoming data
isrcall = 0x01;
char temp;
temp = RCREG1; // read the incoming data
if(temp=='$' && new_rx==0) //if first char of a GPS string..
{
index = 0; //reset index
reading = 1; //from now on go to else if
}
else if(reading == 1) //in middle of GPS sentence
{
ctxt[index] = temp; //load it up
index++; //increment index
ping = 1; //this is for debugging
if(index > 63) //thats more than enough data
{
index = 0; //reset index
reading = 0; //no longer storing the string
new_rx = 1; //"ding"
}
}
}
}
/*
* Set up my ports
*/
void init_io(void) {
// This code before the TRIS setup is for switching the RX2/TX2 to proper pins for the dev board
INTCONbits.GIE = 0; //no interruptions please
LATA = 0x00;
TRISAbits.TRISA0 = 0; //Onboard LED
TRISAbits.TRISA1 = 0; //LED
TRISAbits.TRISA2 = 0; //MCU (ON)
TRISAbits.TRISA3 = 1; // input
TRISAbits.TRISA4 = 1; // input
TRISAbits.TRISA5 = 1; // input
TRISAbits.TRISA6 = 1; // input
TRISAbits.TRISA7 = 1; // input
TRISBbits.TRISB0 = 0; // output
TRISBbits.TRISB1 = 0; // output
TRISBbits.TRISB2 = 0; // PWM1B
TRISBbits.TRISB3 = 0; // output
TRISBbits.TRISB4 = 0; // SCK
TRISBbits.TRISB5 = 0; // PWM1C
TRISBbits.TRISB6 = 0; // SCK
TRISBbits.TRISB7 = 1; // input
LATC = 0x00;
TRISCbits.TRISC0 = 0; // N/W
TRISCbits.TRISC1 = 0; // S/E
TRISCbits.TRISC2 = 0; // PWM1A (output to 4066 control)
TRISCbits.TRISC3 = 1; // MODE SELECT (LAT/LONG)
TRISCbits.TRISC4 = 1; // SET INPUT
TRISCbits.TRISC5 = 1; // input
TRISCbits.TRISC6 = 1; // input
TRISCbits.TRISC7 = 1; // input
ADCON0 = 0b00000000; //don't need any ADC
ADCON1 = 0b00000000; //speed Vref=AVdd, VssRef=AVss
ANSELA = 0x00;
ANSELB = 0x00;
ANSELC = 0x00;
}
void uart_xmit(unsigned int mydata_byte) { //send a character to the UART
while(!TXSTA1bits.TRMT); // make sure buffer full bit is high before transmitting
TXREG1 = mydata_byte; // transmit data
}
void uart_write(const char *txt) //sent a multiple characters
{
while(*txt != 0) uart_xmit(*txt++); //this send a string to the TX buffer
//one character at a time
}
void serial_init(void)
{
//9600 8N1
TXSTA1bits.BRGH=1; // select low speed Baud Rate
TXSTA1bits.TX9=0; // select 8 data bits
TXSTA1bits.TXEN = 1; // enable transmit
RCSTA1bits.SPEN=1; // serial port is enabled
RCSTA1bits.RX9=0; // select 8 data bits
RCSTA1bits.CREN=1; // receive enabled
SPBRG1=51; // here is calculated value of SPBRGH and SPBRGL
SPBRGH1=0;
PIR1bits.RCIF=0; // make sure receive interrupt flag is clear
__delay_ms(50); // give time for voltage levels on board to settle
uart_write("RESET"); // transmit some data for testing
}
void pwm_init(){
//
//Take care if setting up the PWM pins (DISBALE A/D, etc)
//
//Select the 8-bit TimerX resource, (Timer2,Timer4 or Timer6) to be used for PWM generation
//by setting the CxTSEL bits in the CCPTMRSx register.(1)
//
//Load the PRx register for the selected TimerX with the PWM period value.
//
//Configure the CCP module for the PWM mode by loading the CCPxCON register with the
//appropriate values.
//
//Load the CCPRxL register and the DCxB bits of the CCPxCON register, with the PWM
//duty cycle value.
//
// CCPR1L = 0x120;
CCPR1Lbits.CCPR1L = 0x01; //PWM duty cycle
//CCPR2Lbits.CCPR2L = 0xCE; //PWM duty cycle
//CCPR3Lbits.CCPR3L = 0xCE; //PWM duty cycle
PR2 = 0x01; //Timer 2 Prescale
//PR4 = 0xFF; //Timer 4 Prescale
//PR6 = 0xFF; //Timer 6 Prescale
CCPTMRS0bits.C1TSEL = 0x00; //PWM1 TMR2 Selection
//CCPTMRS0bits.C2TSEL = 0x01; //PWM2 TMR4 Selection
//CCPTMRS0bits.C3TSEL = 0x02; //PWM3 TMR6 Selection
CCP1CONbits.P1M = 0x00; //single output mode
CCP1CONbits.DC1B = 0x00;
PWM1CONbits.P1RSEN = 0;
PWM1CONbits.P1DC = 0x00; //dead band delay
ECCP1ASbits.CCP1AS = 0x00;
ECCP1ASbits.CCP1ASE = 0; //Auto-shutdown off
CCP1CONbits.CCP1M = 0x0C; //PWM Mode
//CCP2CONbits.CCP2M = 0x0C; //PWM Mode
//CCP3CONbits.CCP3M = 0x0C; //PWM Mode
PSTR1CONbits.STR1A = 1;
PSTR1CONbits.STR1B = 1;
//T2CONbits.T2OUTPS = 0x0F; //post scaler
T2CONbits.T2CKPS = 2; //16x prescaler
//T4CONbits.T4CKPS = 2;
//T6CONbits.T6CKPS = 2;
T2CONbits.TMR2ON = 1; //Turn the Timers On...
//T4CONbits.TMR4ON = 1;
//T6CONbits.TMR6ON = 1;
}
/*
* Append a string with a character
* append(str, c);
*/
//taken from http://stackoverflow.com/questions/19377396/c-get-day-of-year-from-date
int yisleap(int year)
{
return (year % 4 == 0 && year % 100 != 0);
}
int get_yday(int mon, int day, int year)
//use: int day = get_yday(1, 31, 2013);
{
static const int days[2][13] = {
{0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334},
{0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335}
};
int leap = yisleap(year);
leapint = leap;
return days[leap][mon] + day;
}
void append(char* s, char c)
{
int len = strlen(s);
s[len] = c;
s[len+1] = '\0';
}
void marker(void){
//send a marker frame - 800ms off, 200 ms on
LATBbits.LATB0 = 0;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
LATBbits.LATB0 = 1;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
LATBbits.LATB0 = 0;
}
void one(void){
//send a one - 500 ms off, 500 ms on
LATBbits.LATB0 = 0;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
LATBbits.LATB0 = 1;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
}
void zero(void){
//send a zero - 200ms off, 800ms on
LATBbits.LATB0 = 0;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
LATBbits.LATB0 = 1;
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
__delay_ms(50);
}
void sendtime(void){
/*
*;0
xCALL MARKER ;MARKER FRAME REFERENCE BIT
xCALL ONE ;40min
xCALL ZERO ;20min
xCALL ZERO ;10min
xCALL ZERO ;Reserved
xCALL ZERO ;8mins
xCALL ZERO ;4mins
xCALL ONE ;2mins
xCALL ZERO ;1mins
xCALL MARKER ;MARKER 1
*/
marker(); //marker, frame reference
if (minuteint >= 40){ //40min
minuteint = minuteint - 40;
one();
}else {
zero();
}
if (minuteint >= 20){ //20min
minuteint = minuteint - 20;
one();
}else {
zero();
}
if (minuteint >= 10){ //10min
minuteint = minuteint - 10;
one();
}else {
zero();
}
zero(); //reserved (zero)
if (minuteint >= 8){ //8min
minuteint = minuteint - 8;
one();
}else {
zero();
}
if (minuteint >= 4){ //4min
minuteint = minuteint - 4;
one();
}else {
zero();
}
if (minuteint >= 2){ //2min
minuteint = minuteint - 2;
one();
}else {
zero();
}
if (minuteint >= 1){ //1min
minuteint = minuteint - 1;
one();
}else {
zero();
}
marker(); //marker 1
/*
;10
xCALL ZERO ;RESERVED
xCALL ZERO ;RESERVED
xCALL ZERO ;20hours
CALL ZERO ;10hours
CALL ZERO ;RESERVED
CALL ZERO ;8hours
CALL ONE ;4hours
CALL ONE ;2hours
CALL ZERO ;1hour
CALL MARKER ;MARKER 2
*/
zero(); //reserved
zero(); //reserved
if (hourint >= 20){ //20 hours
hourint = hourint - 20;
one();
}else {
zero();
}
if (hourint >= 10){ //10 hours
hourint = hourint - 10;
one();
}else {
zero();
}
zero(); //reserved
if (hourint >= 8){ //8 hours
hourint = hourint - 8;
one();
}else {
zero();
}
if (hourint >= 4){ //4 hours
hourint = hourint - 4;
one();
}else {
zero();
}
if (hourint >= 2){ //2 hours
hourint = hourint - 2;
one();
}else {
zero();
}
if (hourint >= 1){ //1 hours
hourint = hourint - 1;
one();
}else {
zero();
}
marker(); //marker 2
/*
*
;20
CALL ZERO ;RESERVED
CALL ZERO ;RESERVED
CALL ZERO ;200 day of year
CALL ONE ;100 day of year
CALL ZERO ;RESERVED
CALL ZERO ;80 day of year
CALL ONE ;40 day of year
CALL ZERO ;20 day of year
CALL ONE ;10 day of year
CALL MARKER ;MARKER 3
*/
zero(); //reserved
zero(); //reserved
if (doy >= 200){ //200th day
doy = doy - 200;
one();
}else {
zero();
}
if (doy >= 100){ //100th day
doy = doy - 100;
one();
}else {
zero();
}
zero(); //reserved
if (doy >= 80){ //80th day
doy = doy - 80;
one();
}else {
zero();
}
if (doy >= 40){ //40th day
doy = doy - 40;
one();
}else {
zero();
}
if (doy >= 20){ //20th day
doy = doy - 20;
one();
}else {
zero();
}
if (doy >= 10){ //10th day
doy = doy - 10;
one();
}else {
zero();
}
marker(); //marker 3
/*
;30
CALL ONE ;8 day of year
CALL ZERO ;4 day of year
CALL ZERO ;2 day of year
CALL ZERO ;1 day of year
CALL ZERO ;RESERVED
CALL ZERO ;RESERVED
CALL ZERO ;UTI Sign +
CALL ZERO ;UTI Sign -
CALL ZERO ;UTI Sign +
CALL MARKER ;MARKER 4
*/
if (doy >= 8){ //8th day
doy = doy - 8;
one();
}else {
zero();
}
if (doy >= 4){ //4th day
doy = doy - 4;
one();
}else {
zero();
}
if (doy >= 2){ //2nd day
doy = doy - 2;
one();
}else {
zero();
}
if (doy >= 1){ //1st day
doy = doy - 1;
one();
}else {
zero();
}
zero(); //reserved
zero(); //reserved
zero(); //reserved
zero(); //reserved
zero(); //reserved
marker(); //marker 4
/*
;40
CALL ZERO ;UTI Corr 0.8s
CALL ZERO ;UTI Corr 0.4s
CALL ZERO ;UTI Corr 0.2s
CALL ZERO ;UTI Corr 0.1s
CALL ZERO ;RESERVED
CALL ZERO ;80 year yearint
CALL ZERO ;40 year
CALL ZERO ;20 year
CALL ONE ;10 year
CALL MARKER ;MARKER 5
*/
zero(); //reserved
zero(); //reserved
zero(); //reserved
zero(); //reserved
zero(); //reserved
if (yearint >= 80){ //80th year
yearint = yearint - 80;
one();
}else {
zero();
}
if (yearint >= 40){ //40th year
yearint = yearint - 40;
one();
}else {
zero();
}
if (yearint >= 20){ //20th year
yearint = yearint - 20;
one();
}else {
zero();
}
if (yearint >= 10){ //10th year
yearint = yearint - 10;
one();
}else {
zero();
}
marker(); //marker 5
/*
*
;50
CALL ZERO ;8 year
CALL ONE ;4 year
CALL ONE ;2 year
CALL ZERO ;1 year
CALL ZERO ;RESERVED
CALL ZERO ;LEAP YEAR TRUE
CALL ZERO ;LEAP SEC WARN
CALL ONE ;DST
CALL ONE ;DST
CALL MARKER ;FRAME BIT P0
*
*/
if (yearint >= 8){ //8th year
yearint = yearint - 8;
one();
}else {
zero();
}
if (yearint >= 4){ //4th day
yearint = yearint - 4;
one();
}else {
zero();
}
if (yearint >= 2){ //2nd day
yearint = yearint - 2;
one();
}else {
zero();
}
if (yearint >= 1){ //1st day
yearint = yearint - 1;
one();
}else {
zero();
}
zero(); //reserved
//leap year
if (leapint){
one();
}else {
zero();
}
zero();
zero(); //leap sec warn
zero(); //dst??
zero(); //dst
marker(); //frame bit P0
}
void gettime(void){
hourch[0] = wstr[6]; //HHMMSS
hourch[1] = wstr[7];
minch[0] = wstr[8];
minch[1] = wstr[9];
secch[0] = wstr[10];
secch[1] = wstr[11];
daych[0] = wstr[56]; //DAY1 DDMMYY
daych[1] = wstr[57]; //DAY2
monthch[0] = wstr[58]; //MONTH1
monthch[1] = wstr[59]; //MONTH2
yearch[0] = wstr[60]; //YEAR1
yearch[1] = wstr[61]; //YEAR2
uart_write(wstr);
uart_write(" ");
hourint = atoi(hourch);
minuteint = atoi(minch);
secondint= atoi(secch);
dayint = atoi(daych);
monthint = atoi(monthch);
yearint = atoi(yearch);
year4int = yearint + 2000;
doy = get_yday(monthint, dayint, yearint);
ltoa(doych,doy,10);
uart_write(doych);
uart_write("\r");
}
void lon(void){
}
void determine_mode(void){ //determine lat or long mode
}
int main(void) {
// set up oscillator control register, using internal OSC at 8MHz.
OSCCONbits.IRCF = 0x06; //set OSCCON IRCF bits to select OSC frequency 8MHz
OSCCONbits.SCS = 0x02; //set the SCS bits to select internal oscillator block
__delay_ms(70); //lets think about life a bit before proceeding..
__delay_ms(70);
__delay_ms(70);
ping = 0;
new_rx = 0;
isrcall = 0;
init_io();
serial_init();
//RCONbits.IPEN = 0;
PIE1bits.RC1IE = 1; //Enable RX Interrupt
INTCONbits.PEIE = 1; // Enable peripheral interrupt
INTCONbits.GIE = 1; // enable global interrupt
pwm_init();
ready = 0;
while (1) {
__delay_ms(10);
isrcall = 0;
ping = 0;
if (ready){
LATCbits.LATC2 = 1;
}
if (new_rx == 1) //got our string...
{
if (strstr(ctxt, "GPRMC")) // && ready
{
gprmc = 1;
strncpy((char*)wstr, (char*)ctxt, sizeof(ctxt));
gettime();
}
new_rx=0; //finished with GPS string
}
if (gprmc){
sendtime();
}
gpgga = 0;
gprmc = 0;
}
}
I was asked to create a box that notified by LED if you were too far off a N/S or E/W course. I failed, I doubted the specified GPS accuracy/drift as my Garmin seems to stay pretty steady.. perhaps that’s some integration in the processing?
I started with one of the 18F26K22 TAUTIC development boards I bought from him off Tindie; They’re nice little breadboarding microcontrollers… I’ve recommended them before. I had purchased some GPS modules I got from eBay, so check .. they all have TTL NMEA output, some with 1PPS… and finally some tidbits I picked up out of my parts collection. Wrote some code.. tested it and found my drifting issue. After pondering the number 42 a while, I decided there was no sense in continuing because every idea I had meant something in the specification of the project was out.
I’m not going to go deep into explanation of the code since the project didn’t work but like all failures I learned something. I also expanded my knowledge of XC8 which was nice.. I’ve actively been coding in XC8 for a few months now; in some ways I miss ASM but XC8 does shorten the development time (if you don’t count how long it takes me to figure out atol() should have been used instead of atoi().
This project will be converted into a piece of test equipment of sorts. I’ve been meaning to hook a GPS receiver up to my WWVB transmitter and check it out. Of course WWVB is way more accurate … but if you can’t receive WWVB .. you’re up a creek.
GPS Receiver and Microcontroller outside locked.
Keep in mind this code is un-optimized, and essentially abandoned while I was building the framework. I leave it to you in case you want a jump start on grabbing some data out of a NMEA string.
/*
/*
* File: main.c
* Author: Charles M Douvier
* Contact at: http://iradan.com / 0xEE.net / @chasxmd
* Created on April 4th, 2014
*
* Target Device: TAUTIC.com dev board / 18F26K22
*
* Project: AG GPS Indicator
* Using a PIC to indicate if you're staying in lat/long "groove" by GPS.
* *** This is not complete ***
*
*
* Version:
* 0.1 First build I could prove I had GPS lock
* 0.2 Output GPS on 232 and position set, no debounce, etc.. abandonded
*/
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 4000000 //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=INTIO67, WDTEN=OFF, PWRTEN=OFF, CP0=OFF, CP1=OFF, BOREN=ON
#pragma config STVREN=ON, LVP=OFF, HFOFST=OFF, IESO=OFF, FCMEN=OFF
//WRT=OFF, FOSC=INTOSC, MCLRE=ON
#define _XTAL_FREQ 4000000 //defined for delay
char ctxt[120], wstr[120]; //buff NMEA string, working string
char str[60], c, latstr, lonstr, setstr;
char buffer[32] = "none"; //temp dump
volatile unsigned int ping, isrcall, index, reading, new_rx;
int ready, gpgga, gprmc, mode; //gps associated vars
long long position_set, position_now;
//char *rxdata;
//volatile unsigned int uart_data; // use 'volatile' qualifer as this is changed in ISR
/*
* Interrupt Service
*/
void interrupt ISR() {
if (PIR1bits.RCIF){ // see if interrupt caused by incoming data
isrcall = 0x01;
char temp;
temp = RCREG1; // read the incoming data
if(temp=='$' && new_rx==0) //if first char of a GPS string..
{
index = 0; //reset index
reading = 1; //from now on go to else if
}
else if(reading == 1) //in middle of GPS sentence
{
ctxt[index] = temp; //load it up
index++; //increment index
ping = 1; //this is for debugging
if(index > 50) //thats more than enough data
{
index = 0; //reset index
reading = 0; //no longer storing the string
new_rx = 1; //"ding"
}
}
}
}
/*
* Set up my ports
*/
void init_io(void) {
INTCONbits.GIE = 0; //no interruptions please
LATA = 0x00;
TRISAbits.TRISA0 = 0; //Onboard LED
TRISAbits.TRISA1 = 0; //LED
TRISAbits.TRISA2 = 0; //MCU (ON)
TRISAbits.TRISA3 = 1; // input
TRISAbits.TRISA4 = 1; // input
TRISAbits.TRISA5 = 1; // input
TRISAbits.TRISA6 = 1; // input
TRISAbits.TRISA7 = 1; // input
TRISBbits.TRISB0 = 0; // output
TRISBbits.TRISB1 = 0; // output
TRISBbits.TRISB2 = 0; // output
TRISBbits.TRISB3 = 0; // output
TRISBbits.TRISB4 = 0; // SCK
TRISBbits.TRISB5 = 1; // input
TRISBbits.TRISB6 = 0; // SCK
TRISBbits.TRISB7 = 1; // input
LATC = 0x00;
TRISCbits.TRISC0 = 0; // N/W
TRISCbits.TRISC1 = 0; // S/E
TRISCbits.TRISC2 = 0; // GPGGA DETECT
TRISCbits.TRISC3 = 1; // MODE SELECT (LAT/LONG)
TRISCbits.TRISC4 = 1; // SET INPUT
TRISCbits.TRISC5 = 1; // input
TRISCbits.TRISC6 = 1; // input
TRISCbits.TRISC7 = 1; // input
ADCON0 = 0b00000000; //don't need any ADC
ADCON1 = 0b00000000; //speed Vref=AVdd, VssRef=AVss
ANSELA = 0x00;
ANSELB = 0x00;
ANSELC = 0x00;
}
void uart_xmit(unsigned int mydata_byte) { //send a character to the UART
while(!TXSTA1bits.TRMT); // make sure buffer full bit is high before transmitting
TXREG1 = mydata_byte; // transmit data
}
void uart_write(const char *txt) //sent a multiple characters
{
while(*txt != 0) uart_xmit(*txt++); //this send a string to the TX buffer
//one character at a time
}
void serial_init(void)
{
//9600 8N1
TXSTA1bits.BRGH=1; // select low speed Baud Rate
TXSTA1bits.TX9=0; // select 8 data bits
TXSTA1bits.TXEN = 1; // enable transmit
RCSTA1bits.SPEN=1; // serial port is enabled
RCSTA1bits.RX9=0; // select 8 data bits
RCSTA1bits.CREN=1; // receive enabled
SPBRG1=25; // here is calculated value of SPBRGH and SPBRGL
SPBRGH1=0;
PIR1bits.RCIF=0; // make sure receive interrupt flag is clear
__delay_ms(50); // give time for voltage levels on board to settle
uart_write("RESET"); // transmit some data for testing
}
/*
* Append a string with a character
* append(str, c);
*/
void append(char* s, char c)
{
int len = strlen(s);
s[len] = c;
s[len+1] = '\0';
}
/*
*
* convert the decminal bits of lat or long to integer
* send over RS-232 for review
*
*
*/
void lat(void){
str[0] = wstr[17];
str[1] = wstr[18];
str[2] = wstr[19];
str[3] = wstr[20]; // .21 is a decimal place
str[4] = wstr[22];
str[5] = wstr[23];
str[6] = wstr[24];
str[7] = wstr[25];
position_now = atol(str);
uart_write(str);
uart_write(" ");
//check to set position
if (PORTCbits.RC4 && ready) {
position_set = position_now;
}
if (position_set){
if (position_now > (position_set + 3)) {
LATCbits.LATC1 = 1;
} else {
LATCbits.LATC1 = 0;
}
if (position_now < (position_set - 3)) {
LATCbits.LATC0 = 1;
} else {
LATCbits.LATC0 = 0;
}
}
sprintf(buffer, "%lld", position_now);
uart_write(buffer);
uart_write(" ");
sprintf(buffer, "%lld", position_set);
uart_write(buffer);
uart_write("\r");
}
void lon(void){
//not started
}
void determine_mode(void){ //determine lat or long mode
//not started
}
int main(void) {
// set up oscillator control register, using internal OSC at 4MHz.
OSCCONbits.IRCF = 0x05; //set OSCCON IRCF bits to select OSC frequency 4MHz
OSCCONbits.SCS = 0x02; //set the SCS bits to select internal oscillator block
__delay_ms(50); //lets think about life a bit before proceeding..
ping = 0;
new_rx = 0;
isrcall = 0;
init_io();
serial_init();
//RCONbits.IPEN = 0;
PIE1bits.RC1IE = 1; //Enable RX Interrupt
INTCONbits.PEIE = 1; // Enable peripheral interrupt
INTCONbits.GIE = 1; // enable global interrupt
ready = 0;
while (1) {
isrcall = 0;
ping = 0;
if (ready){
LATCbits.LATC2 = 1;
}
LATAbits.LATA2 = 1; //startup heartbeat LED
__delay_ms(1);
LATAbits.LATA2 = 0;
if (new_rx == 1) //got our string...
{
if (strstr(ctxt, "GPGGA"))
{
gpgga = 1;
strncpy((char*)wstr, (char*)ctxt, sizeof(ctxt));
}
new_rx=0; //finished with GPS string
}
if (gpgga) {
LATAbits.LA1 = 0;
if(ctxt[42] == '1') //this is the 43rd bit but we didn't drop the $ into the buffer
{ //If "$GPGGA" NMEA message has '1' sign in the 43rd
//position it means that tha GPS receiver has a position fix
//
ready = 1; //This is my "locked" variable for future code
LATAbits.LATA1 = 1; //LOCK LED
}
}
if (ready) {
if (mode){
}
if (!mode) {
lat();
}
}
__delay_ms(149); //delay don't really even need to update this often
}
}
If you noticed my posts/week is way down.. well it’s summer. This will happen every summer. My daughter is home and so my time gets happily gobbled up by her 🙂 I’ve got a huge backlog of projects.. thankfully the day job has eased off a bunch. I’m working on a 0xEE project which I probably should have been doing today.. but I needed a break. Also I recently found out our annual backpacking trip is going to be a bit more intense; I’ll have to train appropriately .. so less time on the bench. It’ll be this way until September I imagine.
I just finished up a basic tutorial of using TIA-485 (RS-485/EIA-485) with a PIC micro on 0xEE.net.. this will be part one of at least 2 or 3 articles.
Wow, an action packaged summer so far… no much bench-time unfortunately but work has let off and I’m working sub-50 hour weeks again thankfully. I did get to spend some time this weekend on the bench but really not much. I worked on an article for 0xEE.net and a little fixing for the wife. I did grab my F550 for its first flight (and mine on something larger than one of those micro-quads as well!). I had no intention of filming this… but my wife ended up taking a poor quality video off a cheapo-camera not meant for it. I’m glad she did.. 🙂 I had a visitor.. some dog being walked couple decided to take an interest in the loud flying thing in the air.. it was a little nerve-racking because I didn’t want any accidents but luckily zero problems and no crashing! I can see the appeal of FPV .. it’s a little hard to determine pitch when they get out a bit. I think I’ll have to invest in something like that.
So here is the grainy video of some dog enjoying his day..
Natalie also took an interest in refreshing her soldering skills and was bragging to her uncle she had been soldering since she was four and was better at it than him… I had her soldering one of the waveform generators I made a PCB for without the proper silkscreen.. good times.
I’ve returned from vacation and brought back a ton of tidbits to share over the next few weeks.
I left the beautiful Pacific Northwest to work on my ranch house in Meade County, South Dakota. I had a number of projects I hoped to complete while there and got through a fair portion of my list that was mostly filled with “wishful thinking” mini-projects. Not all of these are electronics based but bear with me, there are some items of interest.. no guarantee it’s you who is interested though 🙂 I also hit up an AM site with one of my best friends and scored some goodies!
Water: My artesian well has low flow, this isn’t crippling but it can be a hassle. I’ve installed a water tank with a float that allows the well to fill a tank through a 3/4″ in-ground sprinkler solenoid. When pressure drops and the well booster pump kicks on it sucks every bit of water it can including any air it can find out of a contentiously flowing drain into a stock tank a couple hundred feet down the line. Now I’ll have a reservoir to provide extra water on the fly and filter some slight sand in the water supply.
Pump and Water Tank in the basement
Sewer: I had a collapsed sewer line… talk about the shits! 😀 I thought this was about all I would get done on my vacation as I was going to have to hand dig the line.. it was about 12 wide, 5 foot down. Luck day, I had a good friend stop by and helped me out a bit… that took off a few minutes of rockin’ the shovel.
With all that work out of the way I had some time to meet up with a friend at an AM broadcast site while he was performing some maintenance. I used to apprentice under him but ended up going a different career route. Not sure I made the right choice some days?
I grabbed my Rigol spectrum analyzer (you bring yours with you on vaca as well, right?) and threw a piece of wire into the input about a hundred feet away from the tower… the station is on 810KHz AM.
marker was obviously not on the peak on the reading above.
I took a ton of readings, compared mine to a much more expensive SA (very satisfied with the results) as well as taking some readings on a 948MHz STL transmitter.
I scored a nice directional sampling line and a bunch of SMA connectors with coax, a 20 watt digital OTA cable transmitter and a ton of other little goodies while I was at it. I great score. I got a VCXO, some filters, attenuators and just a ton of stuff I’ll check out here and there.
Finally, I’ve got some video to edit and drop on the YouTube channel as well but I’ll get to that in the coming days.
