Small oled malfunction

stevecoulson

New Member
Hi, I have just bought an axe131y oled screen and managed to get it to work with a coin acceptor from ebay. It has now started to play up. When I first got it to work it displayed PICAXE.COM when the power was applied. Now it shows 4 characters that look a bit like 6A#q. When it is activated via the coin acceptor instead of displaying
"£1 paid" as before, it now changes to 4 more characters that look like a backwards upper case E, alpha, theta and an h. Does anyone know what's going on?
 

Technical

Technical Support
Staff member
Disconnect the serial wire to the AXE131Y and then re-power up again. Does the welcome msg display again now?
 

stevecoulson

New Member
Disconnect the serial wire to the AXE131Y and then re-power up again. Does the welcome msg display again now?
I have disconnected the 3 wire connector and re-powered up. It comes up the same. As to whether I have reprogrammed the 18M2, all I can say is 'not intentionally'. The unit
could have touched another live wire as everything is a jumble of wires and the connections on the back of the unit are unprotected. Can I reprogram it somehow?
 

stevesmythe

Senior Member
Not sure if anybody else has any suggestions but you can re-install the original firmware by visiting this page and copying and pasting all the code into a new project in the Picaxe Program Editor. Make sure you select the correct Picaxe type (18M2) and connect your programming cable to the socket on the AXE131Y driver board (not the socket on whatever Picaxe board you are using to run your own programs). Press "Program", then you can power-up again when it has finished the download.
 

stevecoulson

New Member
Not sure if anybody else has any suggestions but you can re-install the original firmware by visiting this page and copying and pasting all the code into a new project in the Picaxe Program Editor. Make sure you select the correct Picaxe type (18M2) and connect your programming cable to the socket on the AXE131Y driver board (not the socket on whatever Picaxe board you are using to run your own programs). Press "Program", then you can power-up again when it has finished the download.
Tried that stevesmythe but no change. I did it twice just to be sure. I deleted the '#use LCD' the first time although it was faded and didn't the second time but no change. Still those funny characters. The funny characters are still changing though when I simulate the coin acceptor signal so something is happening. Thanks for your advice. Maybe it's time to buy another oled but this time mount it in a protective box.
 

stevesmythe

Senior Member
Don't give up yet!

What are you using to power the various components? Can you try just connecting a 4.5v battery supply to the AXE131Y board with nothing else connected and see if you get the welcome message?
 

AllyCat

Senior Member
Hi,

I ... managed to get it to work with a coin acceptor from ebay.
You haven't told us anything about the coin acceptor, nor how you "managed" to get it to work, but presumably the coin acceptor transmits some RS232 (serial) data? What you described sounds very much like an "incompatibility" in the communications with the PICaxe, such as baud rate or polarity.

Since it was working and in view of the potential "accident" it's certainly possible (maybe probable) that the PICaxe/OLED has been damaged. But the methodical process is to separate the coin unit and AXE131 and test which is not working "as expected". It may be possible to do that entirely using the "Terminal Emulator" within the Program Editor (again, information about whether you're using PE5 or PE6 would be helpful), or perhaps by using some other Terminal Emulator software (or even tests with a multimeter).

Cheers, Alan.
 

stevecoulson

New Member
Hi,



You haven't told us anything about the coin acceptor, nor how you "managed" to get it to work, but presumably the coin acceptor transmits some RS232 (serial) data? What you described sounds very much like an "incompatibility" in the communications with the PICaxe, such as baud rate or polarity.

Since it was working and in view of the potential "accident" it's certainly possible (maybe probable) that the PICaxe/OLED has been damaged. But the methodical process is to separate the coin unit and AXE131 and test which is not working "as expected". It may be possible to do that entirely using the "Terminal Emulator" within the Program Editor (again, information about whether you're using PE5 or PE6 would be helpful), or perhaps by using some other Terminal Emulator software (or even tests with a multimeter).

Cheers, Alan.
Well, I haven''t been entirely truthful by implying that I am using the coin acceptor to activate the oled. The coin acceptor needs a 12 volt supply but acts as an open drain (thanks to Dave at Southampton Makerspace for diagnosing this and explaining to me what an open drain is) so it simply sinks whatever voltage it is given. To avoid having the 12 volt supply as well as the 5 volt for the Picaxe, I have pulled up the relevant pin on the 08M and have been using a small push button to simulate pulses combined with the Count command eg count 3, 4000, w1. if I click 5 times within the 4000 miliseconds the oled funny characters change to different funny characters. So something is working but not in the right way. I think now that one of the solder contacts on the back of the oled might have touched the 12 volt supply and done some damage to the 18M2. So, I think the only thing to do is replace the 18M2 and re-program it. I will try that and report back. Bye the way Alleycat, my Picaxe Editor is years old so must be PE5. If at first you don't succeed, try, try, try the Picaxe forum.
 

inglewoodpete

Senior Member
I would try a more methodical testing of each part of the process to determine what is happening; where and then why.

Start with disconnecting the AXE133 from the OLD and program the 18M2 to toggle each of the 6(?) pins that drive the module. If you don't have a logic probe or oscilloscope, use an LED+330 ohm resistor to ground. If that works, plug the OLED module in and re-apply power with the same code in the 18M2. Do the pins still toggle as before? You should be able to isolate the offending part using a method like this.

I remember, from several years ago, that my OLED module had to be fully power cycled during code development to get it to initialise properly.
 
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stevecoulson

New Member
I would try a more methodical testing of each part of the process to determine what is happening; where and the then why.

Start with disconnecting the AXE133 from the OLD and program the 18M2 to toggle each of the 6(?) pins that drive the module. If you don't have a logic probe or oscilloscope, use an LED+330 ohm resistor to ground. If that works, plug the OLED module in and re-apply power with the same code in the 18M2. Do the pins still toggle as before? You should be able to isolate the offending part using a method like this.

I remember, from several years ago, that my OLED module had to be fully power cycled during code development to get it to initialise properly.
Cripes Inglewoodpete! Your have more confidence in my abilities than I do. The axe 131y has 16 soldered contacts and I have no idea what any of them do. I have taken the easy way out and ordered a new serial driver from the Picaxe store. When it arrives I will solder it in and say a small prayer.
 

stevecoulson

New Member
Cripes Inglewoodpete! Your have more confidence in my abilities than I do. The axe 131y has 16 soldered contacts and I have no idea what any of them do. I have taken the easy way out and ordered a new serial driver from the Picaxe store. When it arrives I will solder it in and say a small prayer.
Well, the new driver arrived but first I had to remove the old driver. This involved removing a 16 pin header and I foolishly tried to de-solder it all at one go. I couldn't do it so I got a bigger soldering iron. I still couldn't do it so I cut the 16 pin header down the middle and removed the pins one by one. I soldered in the new driver but nothing. I think I put so much heat into the screen module that I did it some damage. Anyway, I ordered another oled kit (this time the 2 by 16 screen) at the same time as the driver and that is now working fine. So, two lessons learnt from this : protect the exposed contacts on the back of the oled screen and don't use too much heat when de-soldering. Thanks for all the advice.
 
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