28Xs won't program...!

nbw

Senior Member
Hi all, I have a couple of old 28Xs (16F873) that I cannot download a program to, or check the firmware of. Any other chip is fine - 08M, 18X, 28X1, etc. But not these 2 28Xs I've had sitting in the box for a while. I can program an 18X, fine, then try the 28X, no response, 18X again, fine.

I've tried different USB ports. Rebooting the PC. Checked all pin voltages. Did the little LED test to check the serial etc (on the software Options tab). No luck.

I've tried on 3 AA batteries, different resonators, even on the AXE022 board - they simply refuse to program. I've tried voltages from 4.5 to 5.1V.

Has anyone else had trouble with these - maybe they were part of a faulty batch? I've bought tons of PICAXEs before - only these 2 have given me any trouble. I've even tried uninstalling v531 of the software and upgrading to v532. No luck.

I need one desperately for the project I'm making (son's wireless cricket board) so if this has been a problem in the past, I'll need to urgently (and nicely) ask the PICAXE folks to perhaps send me a couple. If not, I'll return to pulling my hair out.

Any ideas, anyone?
 

inglewoodpete

Senior Member
I dug out my only (now retired) 28X and arc'd up its transistors for the first time in several years.

It seemed to be working (it flashed a led on Out0) but I couldn't read the firmware or program it either. Then I realised I had a 16MHz resonator connected. Remember, you must connect a resonator to this model of PICAXE.

I had to set the speed to Options/Mode/Options to 16MHz and everything worked again. I am using a straight serial cable on a 5-year old desktop PC.

If you can't get yours going, send me a PM and I'll post it to you.
 

hippy

Technical Support
Staff member
Have you tried Hard Reset, power-off then power-on just after issuing a Firmware Check ?
 

nbw

Senior Member
Hi Hippy, yes - I've all combinations of that. Quadruple-checked the reset pin, soft-reseting, hard-reseting, it's really bizarre. Every other type of picaxe I have is fine - 08M, 14M, 20X2, 18X, 40X etc. About a month or two ago, I programmed some 28X1s and they were fine. Just these cheeky monkeys.

@Inglewoodpete: cheers for the offer there. I'll seriously consider that. Technically speaking, this project doesn't specifically need a 28X, it's just I don't have any 28X1s or X2s, and the PCB is all made up.
 

nbw

Senior Member
well, I retried the 28xs. They cheerfully stuck 2 pins up at me in rude gestures.

So, I bit the bullet and made a different board for my 40x1, which is working fine.

On a vaguely related note, I ordered some 20x2 smds the other week, and I was sent the wrong ICs (groan). Some weird DIP packages with PIC18F something on them. Def. not SMD 20X2s!!
 

nbw

Senior Member
p.s. I also meant to say thanks to the kind folks who offered to send 28xs to me. I appreciated that.
 

westaust55

Moderator
p.s. I also meant to say thanks to the kind folks who offered to send 28xs to me. I appreciated that.
Yes there are some very kind folks out there.
As examples,
BCJKiwi has "loaned" me some MCP23017 i2c IO Extender's so I could advance a project when an order was delayed and then none readily available.
KTarke sent me some 1-wire chips to experiment with where a chip I was keep to do some experiements with were found to be no longer available.
 
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