08M2 not being recognised to download programme

J

jensmith25

Senior Member
I have a 08M2 chip in a commercial PCB which I can't get my programme to download to. I bought two of the same boards and after I couldn't get the first one to work I soldered up the second PCB but it's not working either.

I've checked it's not the chip which I can programme on a different PCB no problem. I tried checking the various points with a multimeter and it's showing that power is being delivered to the switches and the IC socket. I've also checked with the continuity setting and can't find anything wrong.

I've tried programming the chip on a different board and then plugging it into this board to see if it will flash any of the LEDs but that doesn't work either.

I've also tried a hard reset several times and a different 08M2 chip.

I know the cable is fine as I've been able to download to two different PCBs today.

I'm now stumped and assume there's something fundamentally wrong with my PCB. If it was just one PCB I would think it was dodgy soldering but I was very careful with the second PCB so it must be something else.

Any ideas?

Photo attached.
08M2_PCB.jpg
 
J

jensmith25

Senior Member
hippy said:
You can program the 08M2 in a board which does work, get it to exercise its outputs, then check what works when moved to the other board.

There was a problem in the past where the same model of board had a tracking error so it would never work. It might be worth checking that ...

http://www.picaxeforum.co.uk/showthread.php?16186-hardware-not-connected
Click to expand...
Hippy - I tried programming the chip on a different board and then transferring it but it still didn't work. The other 08M PCB I've got is the Picaxe servo board and it has 3 pin outputs so I wasn't sure if / how I could connect an LED to it?

That's very interesting about the PCB error. I will try your wire link fix just to see if that solves the problem as two boards not working is very suspicious! I've been trying re-soldering joints and faffing about with these for the last two days so I would have thought I'd have stumbled upon a fix by now.
 
J

jensmith25

Senior Member
Hippy - I tried a wire jumper just to test as you showed in the other thread to link 0v to LED4 and the programme downloaded instantly!

Looks like they never fixed the issue :(

I have another question - the LEDs still are not working - looking at the PIN diagram it looked like the 08M2 was named with C.1 etc pins. Is this correct?

It's just supposed to be a simple flashing sequence of each LED in turn.

Code: 
#Picaxe 08M2 

main: high C.0
pause 400
low C.0
pause 400
high C.1
pause 400
low C.1
pause 400
high C.2
pause 400
low C.2
pause 400
high C.4
pause 400
low C.4
pause 400
goto main
 
Technical

Technical

Technical Support
Staff member
Unfortunately the design of that third party PCB is terrible. Not only is the ground track broken, one of the LEDs is on pin C.3, which is an input only pin. So that LED will never ever work....
 
rq3

rq3

Senior Member
JimPerry said:
Tends to look cloudy /gaps in the solder flow - much more common now with lead-free solder being pushed on home users. I always use proper "old school" Multicore leaded. :rolleyes:
Click to expand...
I have sworn by Ersin Multicore for almost 40 years. Just ordered another 1 pound (weight, not cost) this week, and it's getting very difficult to find RMA (rosin, mildy activated) in the smaller wire sizes. When 63/37 alloy becomes unavailable, I'll probably take up knitting. Unless aluminum knitting needles become ROHS. And they will. After all, aluminum causes Altzheimers, and we might jam a knitting needle into our brains. I know I'm tempted when I see national economies shrinking due to government "oversight".
 
W

westaust55

Moderator
There are no connections on the PCB between the 8-pin chip and the input and output circuits.
You need to install some wire links from the solder pads near the IC socket to the solder pads near the input (or output) circuits.
This is mentioned in the third party instructions.
See page 3 of instructions second paragraph under "using the inputs and outputs".
 
W

westaust55

Moderator
Technical said:
. . . one of the LEDs is on pin C.3, which is an input only pin. So that LED will never ever work....
Click to expand...
None of the inputs and output circuits are directly connected to the IC pins with PCB traces.
The end user must install wire jumpers to link in input or output circuit to an IO pin as necessary.
But neither is there mention that IC leg 4 (pin C.3 on a PICAXE) can be used as an output when making these connections.
 
rq3

rq3

Senior Member
jensmith25 said:
How do you tell a dry joint? Just for future knowledge too.
Click to expand...
A good solder joint should flow like a drop of water on a paper towel. It should wet all of the metal parts, and be shiny when cooled.
A bad solder joint will ball like a drop of water on a Teflon pan, and will look frosted when cooled.

Lead based solders act like water on a paper towel. Non-lead (Rohs) solders DON'T act this way. They may flow (good), but may not (probably won't) be shiny (maybe not good).
If Rohs solders flow, you MAY have a good joint, whether it's shiny or not. If they don't, you have a bad joint. The difference is, you used to be able to tell. Now you can't, without pretty drastic testing. With all of the electronics in the world today, I'd guestimate that more people have been killed by Rohs solder, than were killed by lead in solder. It would make an interesting PhD thesis.
 
J

jensmith25

Senior Member
westaust55 said:
None of the inputs and output circuits are directly connected to the IC pins with PCB traces.
The end user must install wire jumpers to link in input or output circuit to an IO pin as necessary.
But neither is there mention that IC leg 4 (pin C.3 on a PICAXE) can be used as an output when making these connections.
Click to expand...
Ok, I see where I've gone wrong. Having used the other boards where you didn't have to do that I obviously misunderstood the instructions.

Does that mean I can use LED 3 on pin C.3? When I was writing the programme and checked the syntax it said C.3 was input only.

I'm still new to Picaxe.
 
J

jensmith25

Senior Member
Thanks for the info on the solder. I use Warton Metals Omega II rosin free, lead free solder. I sell my products so I can't use leaded solder. The Omega II is actually pretty high quality and I've been very happy with it. It does give a shinier joint than some other lead free solders I tried.

I think the joints are ok. I think it's the PCB and my error in not realising I needed to connect the outputs to the chip with wire links.
 
W

westaust55

Moderator
jensmith25 said:
Ok, I see where I've gone wrong. Having used the other boards where you didn't have to do that I obviously misunderstood the instructions.

Does that mean I can use LED 3 on pin C.3? When I was writing the programme and checked the syntax it said C.3 was input only.

I'm still new to Picaxe.
Click to expand...

No, on the PICAXE 08M2 pin C.3 is only usable as an input. (sorry I did not phase well in my earlier post).

On the third party board you have there are pads for each IO pin. Then for each LED (output) circuit there are pads. You can connect any PICAXE pin other than C.3 to any of the LED output circuits.
 
J

jensmith25

Senior Member
Just to let everyone know that I got it working. Once I connected the pins and the 08M2 to 0v it worked no problem. Thanks for all your help.
 
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