My first working circuit that I designed was based on the Motorola MC1377. It’s a RGB to NTSC encoder. I am pretty certain I actually still have the chip stored away in my linear/analog microchip parts storage. Apparently they are still available NOS on eBay. I can’t claim that I designed it myself; I’m certain my best friend of the time, Jason G., likely had assisted and designed some of the circuit. At the very least he had a lot of input. It was decades ago, who has that kind of memory? Jason had gotten me interested in “the best” computer of the time. The Amiga 500. I don’t know if it was the best home computer of the time but it certainly was in front of the pack. A powerfully Motorola 68000 and color computing when the 8088 just got 4-color CGA! The Amiga had been around for a while why I bought mine; Long enough for me to buy a refurbished A500 from a commodore shop in north Kent/Tukwila, WA. Jason stayed overnight and we stayed up until the single digits of the morning building this circuit because I had not yet saved enough money to buy the A 1084S monitor… the time had come.. my carpet sporting an extra burn mark from a soldering iron. I was 15 or 16 at the time and I usually soldered on the floor, there were already a number of burn marks by then. We powered up the circuit and plugged it into the Amiga and then my TV… Success! Well kind of.. everything was very purple but the output was perfectly usable. The start of my love affair with Amiga computers and a further solidification of my primary hobby; electronics.
I’m off to LA for some training this week. Hopefully I get some programming done on my projects. I brought a small “go bag” of electronics for out-of-town work. Hopefully the TSA doesn’t give me too much trouble. I’m sure a bag of electronics is a scary thing for those who don’t know what they’re looking at.
Melissa and I have been out of town for a little while. I was hoping to blog on the road but it just didn’t happen. That midwest weather is in a nasty way; I don’t miss winter weather at all. So I have a little more work on two posts I’m working on but I wanted to update the blog for if no one else myself. I need a little brain purge… I have a lot of stuff to work on.
When I got home I had a dozen and a half packages or so from China. A ton of fun stuff.. most of it was for the little robot I’m working on. I also brought back a ton of stuff from my house (in a storage room) that I have left behind.
On our travel across county we stopped by our house in South Dakota and picked up a bunch of our items in storage. I brought back a few boxes of miscellaneous electronics including a lot of older projects I built years ago.
Look at that pile of stuff! A part of one box of old projects I built. Only a few more boxes to go! I got excited about a bunch of copper clad board that turned out to be really cheap; lame!
While out of town a mailbox and a half of sensors arrived from China (eBay)! Time to get building.
Sensors! I guess it’s time to get building. I’m not sure what I’ll use.. I’ll just tinker around until I find what I like.
So I’ve etched PCBs by sharpie.. I’ve used the tape and stencils… even photo etching which provided decent results. With all the talk in the IRC chat room I finally decided I needed to try out this professionally built business.
“My first PCB”… that I didn’t etch myself. The white stencil isn’t right but I knew it would be that way and I was in a hurry to get it on the way. It looks great. I haven’t checked out all the circuit paths but everything looks good. I decided on OSH Park because he is local-ish and seems like a decent guy. The preview feature is nice on his site.. and the price was reasonable. (yeah, I know.. it’s just a proto-board.. I didn’t build it for any specific reason).
Check out the motor controller heatsink!
Finally I got these tiny heat sinks I ordered .. (look at the motor controller on the robot platform). The motor controller is the same one I used for my Roomba Sumobot… it got very hot a few times I’m hoping to avoid those issues this time around with this heatsink that comes with some sticky stuff that hopefully conducts heat well. It was a 10 pack.. pretty cheap.
That’s it! I need to get along with my other posts…next week I’m out-of-town for training; maybe I’ll get something done then? 🙂
While browsing for “goodies” on eBay I ran across a $9 robot chassis. How can you go wrong for $9? I haven’t built a robot since Talus my sumo Roomba, so I thought why not.
If you’re looking for something like the model I purchased, check out eBay and do a search for “Robot Chassis”. Adam Fabio of TheRegnineer.com mentioned he has almost completed working on a product that is similar. I’m guessing you can look for Adam’s product at his Tindie Store once he has finished it.
.. Fast forward three weeks for shipping from China.
None of my sensors have arrived but you’ll end up wanting to customize you robot for whatever sensor pack you are interested in anyhow. With that said I haven’t written any code for handling any sensors and at the end of the day this robot is just going to drive straight forward all day long. You can follow the code at the repository I set up for it on github to get the latest updates at…
I’m using the TAUTIC 20 pin PIC development board as it’s only $10 and takes care of the reset switch capacitor and comes on a nice plug-in board if you solder the connectors the same way I did. Use whatever you like but notice I’m using an internal oscillator so you don’t have to worry about getting a specific development board or having a crystal.
I’m also using the Pololu Quick 2s9v1 Dual Serial Motor Controller which is cost me $25, a little on the high side, but I had one from another project so I’m just re-using it and it makes life a lot easier for development.
Check out the photo at the bottom of the post for the basic schematic.
Beginners:
If you don’t already have MPLABX you’re looking at an upwards battle. However if you don’t mind watching a few YouTube videos it’s not up a creek.
1. Download and install MPLABX and the HI-TECH C compiler.
2. Start a project within MPLABX; selecting PIC 16F1509 and choosing the HI-TECH compiler, and create a main file.
3. Copy my code off the github site and drop it into your main file and compile.
You can download the free version of HI-TECH C and MPLABX which is also free. They are both obtained from http://www.microchip.com. MPLABX is an IDE (integrated development environment) which means it’s a program for programming, compiling and loading your software. HI-TECH is a C compiler which works with MPLABX. There are other programming language options such as BASIC and even assembly (I use assembly most of the time). I don’t know of any free BASIC compilers but I’m guessing someone has one. Google might be your best friend if you’re looking to go that route.
If you don’t have MPLABX you probably don’t have a PICKit 3 (or other hardware programming tool). I like the PICKit 3 because it will program all the newer Microchip PICs and it’s just about the most affordable tool for PICs. PICKit3 comes from Microchip or Digi-key. There are alternatives.
The Build:
It took me about 30 minutes to put the chassis kit together last night. It was pretty obvious how it went together which was good because there were no directions. The encoder wheels don’t really attach other than compression, I see issues with that if I end up using them… that’s what you get for $9?
The code I put together this morning in about an hour or two after reviewing the manual for the motor driver online; you should also review this document. The idea with the code was just to test the motors and motor driver. I also selected a high/half/normal speed which you can adjust for your motor’s needs. I believe the highest speed setting you can select is 0x7F, I chose 0x4F for my high speed based on my anticipated desire. Adjust as needed.. but keep in mind your low speed should be set so it doesn’t stall on carpet or whatever you want your robot to be driving around on.
That’s about it for now. Once I get some sensors in I’ll add them and then write the code. I’m still new to C programming but I felt it was a better choice since it seems most popular; I usually write everything in assembler. Check out the photo I posted as it has a basic layout of the circuit and how I set mine up on a breadboard until I receive some prototyping PCBs I ordered.
First step of my cheap chassis robot build… getting the motors turning.
Digikey selected my #digiwish as one of their daily winners! I asked or a new 3M mat for my work bench and it came out looking better than I has hoped for; Thanks Digikey. Unsolicited recommendation: About 90% my breakout boards and specialty items come from Sparkfun or Tindie, but for all my parts and other items such as my Microchip PICkit 3, I shop at Digikey. They have good pricing and a lot of times I get my order the next day with the cheaper shipping despite being half way across the country.
The before and after photo! (left to right it’s actually after and before)
I was a winner of #digiwish from @Digikey this year. I wished for a new mat for my workbench… I knew I wouldn’t buy one myself. Thanks to Digikey my bench has a fresh new look!
I saw a little probe for monitoring soil on eBay.. $1.69 and free shipping.. purchased! Okay.. its a lame little PCB with some electronics I won’t use but still, nifty. I didn’t have much on my plate today and I was pretty sore from a solid hike yesterday so I was riding the bench seat today. I built a little front end circuit mated to a little MCU built on a Jayson Tautic 8 pin dev board with a 12F1840. It dumps serial out to a $3 433Mhz transmitter when the soil is low on water (still need to write some sleep code).. on the other side the receiver and well I don’t know yet. Honestly I started with thinking about a XPORT but I haven’t made my mind up.
Work in progress…. watching dirt dry.
So, a funny side effect: My wife was frustrated that she couldn’t get our wireless Christmas lights to turn on. Heh, well “Ooops!”… shocker, I had to turn my circuit off. So next I’ll work on the receiver side. I’m thinking my poor plants need to text message me when they’re thirsty? I’ll drop code later when it’s more complete.
And yesterday! I hiked past this pretty awesome frozen water fall (and two others) on my way up to Lake Serene. Last year we got stopped by a nasty avalanche field.. this year is was just solid ice. Thankfully I had my Kahtoolas.
I am doing some experimenting with some small signal magnetics and a thought crossed my mind to ask the super-cool @tymkrs IRC channel gang if I was missing the boat on stripping enameled wire. Turns out I was….
Warning: I will not be held responsible for wives who are upset about missing emery boards.
The winner was the emery board. My wife might have to donate one to the cause.
The conversation:
<chasxmd>JohnS_AZ, is there a magic formula to removing the enamel off magnet wire?
<tautic|mobile>Stupid traffic
<mgburr|work>good exacto knife and scrape, or heat to 400f
chasxmd: hit it with your iron that is set higher then the melt temp
thanks for the tips, I've always gone exacto knife and felt there had to be a better way
<johns_az>chasxmd: I always steal one of Lisa's emmory boards. :-)
<johns_az>fine sand paper works well.
- scratch quit (Ping timeout)
<mgburr|work>all of the above
So I put these to test! I’m using 30 gauge wire that’s less than 10 years old and was redistributed by GC electronics.
Soldering Iron: Free air and solder pool.
Sanding: emery board and 220 sand paper
Exacto-Knife scraping.
Not tested, but possible future ideas: Blow torch, actually googling to see if there is a tool the industry uses.
So scraping takes a while and it leaves small strips that you end up having to sand or rotate a 30 ga wire and get lucky? On 30 gauge wire, forget about it.. a waste of time.
220 sand paper? probably a lot better on 18gauge+ enameled wire but for small wire it was a hassle and took way too much time testing the conductivity and making sure I had gotten at least almost all the enamel off.
The two reasonable methods for my wire were my wife’s emery board and the soldering iron.
The emery board was the shortest method. I removed a 1/2 inch* section of enamel in just under a minute**.
The soldering iron was looking like a bust because I was free-air rubbing the wire to the tip of my Weller soldering station with some fresh solder on the tip. At 1:15 I hadn’t made a dent in the enamel. I trend grabbed a piece of copper clad board and added a little solder and rubbed the wire with the soldering iron and it turned out okay.
* I live and work in the USA. I use measures of units that I was born and raised on; It’s not lost on me that this is inconvenient for you non-US persons.
** I wasn’t cracked out on caffeine and I was just taking a leisurely relaxed pace through this process.
