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Question

i2c Arbitration lost

posted in IGEPv2
Monday, March 16 2015, 07:59 PM
peter
peter
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I am trying to connect a device to the i2c_2 pins on the IGEPv2. When I try to detect it with
i2cdetect -r 0
I get the message
omap_i2c omap_i2c.2: controller timed out

When I disconnect everything from the IGEP J990 pins and again try
i2cdetect -r 0
I get the message
omap_i2c omap_i2c.2: Arbitration lost

Normally I would expect a list of addresses probed with nothing at any of them. The internet suggests this means 2 MCU's are competing for the bus?
I am unsure of the cause. dmesg and the i2cdetect results are attached.

Peter

Accepted Answer

egavinc
egavinc
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Tuesday, March 17 2015, 09:28 AM - #permalink
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Hello Peter, in the schematic you can observe that the i2c that are you using doesn't have installed the pull-up resistors.
Do you have installed the pull-up?
If not, please add the pull-up and check it again.

Best Regards
Eduard
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Responses (1)
  • Accepted Answer

    peter
    peter
    Offline
    Wednesday, March 18 2015, 04:29 AM - #permalink
    0
    Eduard,

    You are absolutely right. Two 4.7k pullup resistors from SCL and SDA to 1.8v fixed the problem. Thanks so much for figuring it out. I was on a totally wrong track.

    Peter
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