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I2C bus detect not giving correct result #7

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bugobliterator opened this issue Jul 23, 2014 · 5 comments
Open

I2C bus detect not giving correct result #7

bugobliterator opened this issue Jul 23, 2014 · 5 comments

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@bugobliterator
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i2cdetect -r 1 command gives
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- UU UU UU UU -- -- -- -- 5c -- -- --
60: -- -- -- -- 64 -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

This is clearly a wrong response the expected pings were to be from addresses 0x55(Toshiba LED) and 0x77 (Barometer) instead we are getting responses from 0x5C and 0x64. Until this post the result is proved to be this way on two boards on Siddharth's and Victor's board.
i2cset and i2cget also fails to work for all the mentioned addresses.

@vmayoral
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@bugobliterator i've read your reasoning about the conflict between pins 6 and 7 but i still don't get it. According to the datasheet, pin 7 corresponds to SDA (and not pin 6).

@bugobliterator
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@vmayoral you are correct about the pin setup, it was a mistake from my side. I revisited the datasheet and found that pin7 corresponds to SDA. However, this means everything is fine with the pin connections and leaves the non-functioning of i2c devices unexplained. I've tested the Toshiba LED pin connections too, they look fine to me. Even used multimeter to test connections on physical board. Although, It is possible I might have missed something. Also we are getting response from two devices on i2c-1 and BBB has no I2C device connected to i2c2(/dev/i2c-1) but cape has MS5611 and Toshiba LED driver. So i think response is there but it is either received incorrectly or sent incorrectly. In my opinion Logic Analyser might answer these questions.

@vmayoral
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@bugobliterator thanks for clarifying that. Could we hack the MS5611 driver to believe it's in some of those responding addresses? I wonder if it's just an issue with the address or the whole bus is messed up.

@vmayoral
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A change here should do it.

@bugobliterator
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@vmayoral I think the whole bus is messed up as i'm not getting response via i2cset and i2cget. I'll tryout your fix too.

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