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Topic: Mega not reading I2C (Read 215 times) previous topic - next topic

Northof49

I have two mega's.   One reads I2C perfectly, the other one simply won't.  If I run i2c scanner on the one that won't read, I get no results whatsoever.  Should I just resign myself to the fact that this is a hardware problem with the one mega, or is there something else I need to try?

Nick_Pyner

this is a hardware problem with the one mega,
The hardware problem could be improper connection. Maybe inadequate power.

Northof49

I use the same setup and I2C accessories for both mega boards, and one works, the other doesn't.   I've tried it multiple times, and with different I2C devices, and its always the same, simply doesn't communicate with or detect any i2c device on the one mega.

I suppose I could try hooking up a scope to the suspect mega and see if its puts out clock or data.  Maybe its dead as a doorknob.

The mega works fine for all other uses, so its not garbage, but frustrating that it was the first Arduino I ever purchased, and it caused me so much grief with i2c.  I kept asking myself what I was doing wrong when it was the only Arduino I owned.  Then I tried 2 other arduinos, and experienced no problems.

Just thought i'd ask in case there was some jumper or hidden config that could be off.


Nick_Pyner

#3
May 25, 2018, 07:10 pm Last Edit: May 26, 2018, 03:20 am by Nick_Pyner
Just thought i'd ask in case there was some jumper or hidden config that could be off.
I don't think there is. One Mega should be the same as another. I have never heard of the problem before - hence my comment. I guess there is always a first ..

jremington

#4
May 25, 2018, 07:45 pm Last Edit: May 25, 2018, 07:46 pm by jremington
There could be a bad solder connection on one of the Mega boards.

Try connecting a resistor/LED combination to SDA and SCL, and check their function as standard digital outputs (use something like the Blink example).

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