What size pullup resistors are you using on the I2C bus?

Gerald


On Tue, Sep 2, 2014 at 12:29 PM, <[email protected]> wrote:

> Hi !!
>
> I'm facing problem with Custom I2C cape. It's I/o Expander using NXP's
> PCF8574T Expander chip. I'm unable to detect it. I tried every thing
> available on web. Can you help me ? please ?
>
> Here is some output.
>
> root@beaglebone:~# uname -a
> Linux beaglebone 3.8.13 #1 SMP Wed Sep 4 09:09:32 CEST 2013 armv7l
> GNU/Linux
>
> root@beaglebone:~# i2cdetect -y -r 0
>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
> 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 20: -- -- -- -- UU -- -- -- -- -- -- -- -- -- -- --
> 30: -- -- -- -- 34 -- -- -- -- -- -- -- -- -- -- --
> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 50: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 70: -- -- -- -- -- -- -- --
> root@beaglebone:~# i2cdetect -y -r 1
>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
> 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
> 10: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- --
> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 70: -- -- -- -- -- -- -- --
>
> root@beaglebone:~# i2cdetect -y -r 2
>      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
> 00:          -- -- -- -- -- -- -- -- -- -- -- -- --
> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 20: 20 -- 22 -- 24 -- 26 -- -- -- -- -- -- -- -- --
> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 70: -- -- -- -- -- -- -- --
>
> I'm using Beaglebone Black Rev B.
>
> Hope Listen form you soon.
> Thanks.
>
> On Thursday, July 17, 2014 9:17:40 PM UTC+5:30, Johan Korten wrote:
>>
>> I managed to make my own cape (for two XBee modules). It works very well
>> (even sending between the two modules and to the third one on the
>> computer), but:
>>
>> if I use node ./eeprom.js
>>
>> I suspect that my cape is expected to be connected to the fourth (or
>> third if you start counting at 0) i2c bus:
>>
>> /sys/bus/i2c/drivers/at24/3-0057/eeprom instead of
>> /sys/bus/i2c/drivers/at24/1-0057/eeprom
>>
>> So should I fix that in my cape (my cape is default at
>> /sys/bus/i2c/drivers/at24/1-0057 but can be configured to go from
>> /sys/bus/i2c/drivers/at24/1-0054 .. /sys/bus/i2c/drivers/at24/1-0057)
>>
>> Apart from that, I managed to program the eeprom and get it working, but
>> since it uses UART 2 and UART 5 I needed to change /boot/uboot/uEnv.txt
>> to get that working (BBB Rev B so that is why I needed to
>> change /boot/uboot/uEnv.txt instead of /media/BEAGLEBONE/uEnv.txt), but
>> do I need to supply that with my final version somewhere or is it enough to
>> put that in the manual?
>>
>> Sincerely,
>> Johan
>>
>>  --
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