mjf2708
Posts: 8
Joined: Sat Aug 10, 2013 4:42 pm

i2c issues with Adafruit Powerboost 1000C

Thu Mar 22, 2018 1:49 pm

I recently completed paulv's 'RPi Power Supply w. UPS, one button control' (here: viewtopic.php?f=37&t=145954) and added a MAX17043 'fuel gauge', so that I can read battery voltage (I also send this to Domoticz). I'm powering my RPi 2B using the (optional) USB-A socket, and a USB to micro USB cable. However, I failed to get any readings, and running 'sudo i2cdetect -y 1' gave me this:

Code: Select all

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 
30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f 
50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f 
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 
70: 70 71 72 73 74 75 76 77                    
I discovered that the Powerboost 1000C adds charge-rate resistors to the USB D+ and D- lines, to set the charge rate for iOS devices. When I replaced the USB cable with a power-only version, the problem went away, and I get this with i2cdetect:

Code: Select all

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- 36 -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                
Begs the question though: why are data lines present on the RPI's power socket?

mosespi
Posts: 508
Joined: Mon May 12, 2014 3:35 pm
Location: 34,-118
Contact: Website

Re: i2c issues with Adafruit Powerboost 1000C

Sun Mar 25, 2018 11:23 pm

I don't believe any of the full size Pi models have anything hooked up to the micro-usb data lines. Also, I can't really see how the USB power input would have any direct interaction with I2C.. unless you have some strange power and/or ground problem somewhere that you are effecting by swapping cables.

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

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