BasicMicro - Forums

I've been using a Basic Atom 28B chip on an OEM board. I wanted to build a board specific to my application, program the 28B on the OEM board, then move the chip to the new board. The 28B runs the program fine on the OEM board, but when I move it to the project board it's intermittent. It will run for a few minutes to an hour, then just hang up. Sometimes moving a wire will get it going again, often I can just wave a hand over the board, hold it in a certain position and it will run again.

I'm using a 7805 regulator with bypass caps, a healthy nicd power supply. 20 MHz oscillator with the 1 meg resistor. Any ideas, is this just circuit layout and noise? Perhaps my oscillator? Any input would be appreciated.

One more question. Does the Basic Atom 40M have 8 analog ADC inputs. I can't seem to find any data on ADC pins other than the 4 AX(0 - 3) pins.

Scott

Hi. The first thing that comes to mind is the pullup resistor on the MCLR pin. You need a 10K pullup or so on the MCLR. This sounds like you have a sensitive floating input, and this came to mind immediately. You say you have the 1 meg resistor in the oscillator (crystal, right?), but what about the 20 to 22pF caps? Also you have to have the right kind of crystal, but I'm hazy on which you want, series or parallel. And be sure the crystal and support circuits are close to the processor. You might want to search the old forum for "crystal" or something. Or call BasicMicro's tech support. Did you try to copy the OEM board's circuitry when you set up the new board? And of course there's all the usual problems, like feeding inputs to outputs, noisy motors, sudden current surges, arcing switches, and things like that.

'Luck on your project.
kenjj

kenjj,

Many thanks, that was simple. The 10k resistor did the trick. It seems nice and stable now. I must have missed that somewhere. I have been using OEM modules, but it seemed like it was time to take the next step and put the chip on my own board. I've got the board reading 4 analog sensors and one digital input, sending the data to logging PC application via MaxStream radio modems.

Coming from a BS2, I really love these Basic Atoms...

Again, thanks!

Scott

You're welcome. Rolling your own gives an immense sense of pride. And, yes, the Atom is the next natural step up from the Stamp. Next thing you know you'll be sending your board designs to China to have a hundred made for your thriving online OEM module business!

Take care.
kenjj