I2C bus detection

[Abdurrahman Adam]

Hi, I am wondering if I did this correctly. I am trying to see if the default sensor is communication properly after I did some integration with off the shelf pH sensor.

Using this command I would like to see the multiplexer address, but it seems I cant find the adress

i2cdetect -y 0
i2cdetect -y 1
i2cdetect -y 2

I assume from the .py backend that the multiplexer should be communicating in adress 2, but it seems there is no connection

but keep that aside, I can startup my reactor and do readings (OD and thermostat) the value seems okay but I havent done callibration. I just want to know if that is the correct way to check the communication of I2C or chi bio works the other way?

[Abdurrahman Adam]

root@beaglebone:/root/chibio# i2cdetect -y 2
Warning: Can’t use SMBus Quick Write command, will skip some addresses
0 1 2 3 4 5 6 7 8 9 a b c d e f
00:
10:
20:
30: — — — — — — — —
40:
50: — — — — — — — — — — — — — — — —
60:
70:

Here is the respond

[harrison]

THis is a bit of a tricky one since you need to also be toggling the Watchdog circuit on the beaglebone board in order to get such a command to succeed – otherwise the multiplexer may be de-powered.
What I would suggest is getting a simple scan-I2C bus function implemented in the python (app.py) rather than using linux’s integrated i2cdetect command. You could then have this run on the beaglebone and print out the answer which (with the watchdog timer running) should work.

[Abdurrahman Adam]

Hi Dr. Harrison,

Thank you for your helpful reply. Actually I realize that the interface is the most convenient way to see turbidostat connection.

Also, I am wondering if I can use other bus to communicate with integrate chi bio with pH sensor. I understand that the beagle bone have channel 0, 1 and 2 for communication but chi bio multiplexer only use 2nd bus. Is there any specific reason that you dont touch channel 1?

[harrison]

Hello
Those I2C busses are ones on the beaglebone itself/connected to the microcontroller, certainly there is no second bus being used on the cape we made for the beaglebone black, or the chibio reactor. I am not sure if the other busses are actually exposed on any of the beaglebone black header pins. You could look into this if you wished, but it might be a difficult approach. Probably most straightforward is to use the expansion header on the side of the chi.bio reactor which has the usual bus exposed on pins there.

harrison

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