28X2 Problems

[chigley]

Just built a circuit on stripboard with a 28X2, but I'm having some problems.

On first power up, pin B.1 appears to be high. There's an LED wired to this pin, which is lit. When I try to talk to the PICAXE with the programming editor, the LED goes off, then comes back on after the editor gives the error saying "no hardware found".

Power supply is fine.

Are these symptoms of a particular problem? Can't post photos of the board right now, sorry.

Cheers,

Charlie

 

[eclectic]

Just built a circuit on stripboard with a 28X2, but I'm having some problems.

On first power up, pin B.1 appears to be high. There's an LED wired to this pin, which is lit. When I try to talk to the PICAXE with the programming editor, the LED goes off, then comes back on after the editor gives the error saying "no hardware found".

Power supply is fine.

Are these symptoms of a particular problem? Can't post photos of the board right now, sorry.

Cheers,

Charlie

Charlie.

"Empty" your 28X2 then switch on again.

I've got an empty AXE091 board

This program,

#picaxe 28x2

and an LED/res
B1 > res > LED > gnd
produces
NO response when switched on.

Then, check your wiring
VERY carefully.

e

 

[chigley]

I can't 'empty' it because it's a brand new IC and I can't programme it due to the "no hardware found" error. I suppose I could drop it into an older 28X1 board I have so I can erase the programme memory, although it should be empty anyway.

Will check my wiring but I already have and didn't find anything.

Thanks!

 

[Andrew Cowan]

Can you post high res photos of the top and bottom of the board?

A

 

[chigley]

Will post photos ASAP.

Not sure if this will help, but when I ground the reset pin, the LED goes off. Would it help if I dropped the 28X2 into a 28X1 circuit to write a blank programme, in case the 28X2 is just unstable for whatever reason?

 

[MartinM57]

I'd keep everything very simple...

If the 28X2 is fresh from Rev-Ed then I'd put it in a breadboard with absolute minimum circuitry (+v, Gnd and the two programming resistors) and get it working there - and also start the download and THEN power on the PICAXE.

If it's secondhand (i.e previously had a program in it) ... I'd still do that as well...

 

[eclectic]

Will post photos ASAP.

Not sure if this will help, but when I ground the reset pin, the LED goes off. Would it help if I dropped the 28X2 into a 28X1 circuit to write a blank programme, in case the 28X2 is just unstable for whatever reason?

Please look back at post #2.

Clean board. A KNOWN working download circuit.

I've just swapped a 28X2 to another AXE091 board.

It still works. (PE > firmware)

Charlie, please get a clean board,
with a correct download circuit.

e

 

[chigley]

Please look back at post #2.

Clean board. A KNOWN working download circuit.

I've just swapped a 28X2 to another AXE091 board.

It still works. (PE > firmware)

Charlie, please get a clean board,
with a correct download circuit.

e

All sorted 100% stupid error.

Nothing wrong with my circuit at all, other than forgetting to replace a solder joint after resoldering the download socket.

Thanks for all of your suggestions. The fun starts now - adding in the 4066 and the FRAM

 

[Andrew Cowan]

Well done on solving the problem. 99.9% of the time the problem is user error (especially on stripboard!). Always try the chip on a known working board if you have one.

A

 

[chigley]

Well done on solving the problem. 99.9% of the time the problem is user error (especially on stripboard!). Always try the chip on a known working board if you have one.

A

Yeah, my next move would have been to swap it onto a working 28X1 board, then the oscilloscope with assistance from my dad after that!

I was just thrown by the random LED on that output. Hadn't crossed my mind that the download error was being caused by anything else!