22 Apr 2006 The Swirling Brain   » (Master)

Well I'm finally finished making the 30 RBSs! Hopefully that will free up a little of my precious time to do some other things I've been needing to do that have been stacking up.

My little RBS business has helped keep me going for a while now. I guess you could say I finally have a real business now! It barely sustains us, but I've been out of a job for about a year now other than making RBSs and other odd jobs, so I guess it's sort of going. It really needs to make a lot more money before I really will feel comfortable with calling it my day job, but at least it's keeping our mouths feed for now.

When I haven't been making RBSs, I've been working on my computerized RBS. The computer part has been coming along nicely if a little bit slower than I've wanted. I'm hoping to get all of the electronics part finished soon.

I've got about all of the bugs out of the scheduler so that it works fairly well. It can run several processes (10) all at the same time. I have a process servicing the LED, LCD, RTC, Keyboard, Sensors, Buzzers, RF Commander, Elevator Motor, Clock Hand Stepper Motors, Lights, etc. Some processes do dual duty like the keyboard and rf commander are both handled in one process.

I made the 16x2 LCD display big characters by making 8 graphic characters that can be used 4 or 6 at a time per character. They look fairly good. I can display the time in big characters so you can see them far away. When the menu isn't used for a while, it switches to displaying the time.

I got the I2C thing figured out. I had to bit bang it since the pic16F877a eval board I was using didn't wire them right. But no biggie, I sort of wanted to know the ins and outs of it anyway. So I got the RTC clock giving me the time, the EEprom storing preference data, and above all, I've made a pic16f84a i2c port expander to drive the stepper motors for the clock hands. Yep, that's right I bit banged and i2c slave chip too that handles 2 stepper motors and a few LEDs with PWM for dimming them. I'm really liking i2c for distributed computing. I'm thinking it's so nice that I may make some more little i2c modules and such. So basically, right now, I have a main computer that handles the menus and such, and a second computer that handles the steppers and leds and such, and rtc and eeprom all on the same i2c bus (well actually, eeprom is on a separate i2c bus but I'll probably change that). Anyway, I like that i2c bus way of doing things!

I've had a few problems with the DC motor since it likes to reset the processor when I turn it on. I added a few capacitors and it seems to have gone away.

I also had problems with that 1F cap. It poped! I had another and it worked a while and popped too. I guess they're very delicate. I don't know why they popped. I replaced them with 1000uf caps. For the clock, I wired a 100uf cap directly to it's vdd with a diode so when power goes away the 100uf cap powers just it and doesn't power everything else. That keeps the EEprom going for about a minute. That should be long enough for most brief power failures. I thought about putting a bigger cap on it but I added it to the bottom side of the board so it wouldn't look so nasty hacked onto the top so I used the small 100uf cap.

I replaced the non-working buzzer out for a little speaker from an earbud headphone. I made it do low, med, and high pitched with long and short beeps. It's not too loud and it's kind of cute. I don't know if it would cause problems with anything electrically, but it seems to be a good cheap solution.

For the clock hands, I found out the steppers I bought were 24 step steppers. That was a little disappointing because I thought they were 200 step steppers. 24 steps alone is really not good for a clock. 60 or more steps would be ideal. So I switched to using half step logic. That got me 48 steps per rev so that would be ok for the hour hand. For the minute hand I decided to make gears out of wire. Wire gears would keep the look for a wire RBS. I'd have a 12 tooth pinion gear and a 15 tooth drive gear for a 1:1.25 ratio or 60 steps. That just barely is good enough for the minute hand. Really I would have liked double that but making a bigger gear out of wire is harder to make. I have the two opto sensors working for the clock hands so it can tell when the motors are at top dead center then it can position the hands for the rest of the time by steps alone.

Just about everything is working on the electronics. I have some more software I want to add and I still have a whole bank (2k) that I haven't used used and some more here and there.

I'm really looking forward to seeing this clock being built and finished. I have a few other people that seem interested in seeing it working too. Of course, my wife just thinks I'm nuts. I've pretty much learned to ignore her. She just thinks things are cool when they bring in money.

I've downloaded express pcb and sch and played around with it a little. I'm hoping if this electronic RBS thing works out that I may start making a few custom boards so that I don't have to solder everything point to point and kill lots of my time and effort. I think I want to make everything modular and use a standard i2c header on everything with power, ground, SCL, SDA, and a few other pins. Something where I could reuse a module for another project if I wanted. I'm sort of into the electronics stuff again for now since I've just built a few things and hacked some electronics stuff lately.

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