Problem getting a 18m2 program to run on a 20m2

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captnemo

New Member
The program runs fine on an 18m2 but when I down load it to an 20m2 it doesn't run. It's a simple clock program and I've made sure the SCL and SDA are on the
proper pins of the 20m2. There are no other connections to the 20m2, just the SCL and SDA. I've Tried different setfreq, but that has no effect. There is a 1307 clock chip
and a 128 x 64 oled on the i2c bus. The display stays blank after a download. The bread board wiring is the same, the only change is the 20m2.
 
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papaof2

Senior Member
Did you check that the 20M2 has power, ground, etc on the correct pins?
It's very easy for someone to just think "It's two pins longer but everything should be in the same place" which is NOT universally true.
 
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roho

Member
Ahh, I was assuming that the breadboard being used was the PICAXE development board, in which case the power supplies and RxD and TxD lines are automatically taken care of. I'm also confused by the implication that the download to the 20M2 is successful, something that cannot be true if the device isn't correctly powered.
 
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captnemo

New Member
The program say's it has downloaded fine. Any way, I've decided to go with the an 18m2 since I won't be using all the selector switches I used on the last Geiger counter. I'll just press one button, several times, to get to the selected screen, which is what I should have done on the first model, which used a 20m2.
As far as the wiring goes, I built a programmer with three zif sockets. One for the 8, 14 and 20 picaxe's another socket for just the 18 and the last socket for the 28 . The programming port and the power for each type is already connected to the zif socket. I can go from any pin on a picaxe to a breadboard. It also has a built in 5vdc supply and also variable supply 2 to 40vdc. I built it about 7 or 8 years ago.

Thanks for all the help, guys.
 
hippy

hippy

Technical Support
Staff member
The 20M2 has a different footprint to the 18M2 but the software should behave the same, should work equally well if the correct pins are used, wiring is correct., in this case the I2C bus goes to the right pins, has the pull-ups in place.

I would assume the download wiring is correct if the download succeeds without error, and the issue likely to be with the connected circuitry or wiring.

I would suggest running code to check the RTC and OLED worked individually. If neither work there is probably a systemic issue in wiring. If one works but the other doesn't an issue with its wiring. Getting SCL and SDA crossed-over isn't an uncommon error, but simply missing the pull-ups or even power connection isn't impossible.

We don't really have enough information to diagnose what may have been wrong.
 
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