Cannot upload programs anymore

[dusko]

While preparing my PICAXE 18X for tests with an IR receiver, I've initially built a simple LED blinking circuit, uploaded a simple program, and the LED was blinking as it should. I've started adding IR parts and wanted the test the circuit. When I tried to upload my new program, a message about missing device, unpowered device, etc. appeared. I've tried everything, including re-building the download circuit. My tests also showed that all eight outputs are high--if I attach an LED (with a 390 ohm resistor), it stays on.

I've also built a PIC specific minimal circuit and connected my Pickit2 programmer. The programmer immediately detected the device (as 16F88), and I was I able to read the PICAXE's memory (although that read is probably incorrect).

So, before trying to convert my PICAXE 18x to a lowly 16F88 (by erasing it completely), do you have any suggestion how to "unstuck" the PICAXE?

 

[hippy]

Have you built a minimalistic PICAXE download circuit ? Have you also checked the 4K7 reset resistor is in place and any reset button isn't jammed down ? That it stopped working after adding components suggest a wiring or circuit error. The outputs shouldn't go high unless your software sets them that way.

 

[dusko]

Thank you for your help. Yes, I did build again a minimalistic circuit, and checked the 4.7k resistor. I'd even removed the reset switch, just to be sure that it does not interfere with my setup. The original program was very simple

symbol counter = b1
symbol LED = 4

main:
	for counter = 1 to 15
		high LED
		pause 500
		low LED
		pause 500
	next counter
	pause 1500
	goto main

Re all outputs high (cannot go high unless programmed to do so)--that's exactly what I am thinking. I have no explanation what happened. Especially taking into account that the only program I uploaded was the one above.

Thanks again.

 

[Dippy]

If you disconnect the external components/devices will the PICAXE programme OK? (obv leaving the download circuit in place!!)

I had an issue in the dim'n'distant where i couldn't programme an 18X when certain things were connected. I can't be more specific because I can't remember.

I assume you haven't muggered it now by connecting a PIC programmer??

 

[moxhamj]

Don't erase it yet. What is your code? Did it have any serin commands or very long delays? If so, these can give the appearance of a dead chip and you need to turn the chip off then power up the chip just after hitting the download button.

Failing that, I find it helps a lot to have some spare chips lying around. At least that can tell if it is a miswired circuit or a zapped picaxe.

 

[dusko]

Thank you for your suggestions. The only program that should be in my PICAXE is the one shown above. I am using the minimalistic circuit, and I also checked my serial connection by following the procedure described in help. The voltage is -0.58V (when the LED is off) and +5.7V (!) when I click the green LED. Re Pickit 2 programmer -- I don't think I damaged the chip just by connecting it to the programmer. I've read the memory content, and avoided any writes -- I am sure it would be the end of the chip existence as a PICAXE. (It would be its third incarnation--again as a PIC 16F88.)

 

[hippy]

Try a hard-reset download with your minimalistic download circuit. Hold the reset button and don't release or don't apply power until you have initiated a download ( PICAXE -> Clear Hardware Memory ) from the Programming Editor and the pop-up shows "Connecting to hardware..." in its menu bar. That will hopefully wake the PICAXE out of any slumber.

You can also try the same with an identify firmware from the View -> Options menu. Click the "Firmware?" button then immediately power-up the chip or release from reset.

When you power down the circuit make sure the voltage to the PICAXE has dropped before powering it up again. A 220R or upwards across +V/0V on the circuit board helps there.