Beaglebone Black to i2c obd-ii adaptor b ..

[eoinverling]

Hi,

I've a beaglebone black and a model b, i2c, obd-ii adaptor

When connected to the i2c ports on the beaglebone (and to GND, needed that to get adaptor to work!) ... I can see 2 devices on the i2c bus:-

root@beaglebone:~# i2cdetect -y -r 1
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 -- -- -- -- -- -- -- --
60: -- -- 62 -- -- -- -- -- 68 -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

It appears there are 2 x devices, at address 0x62 and 0x68. Taking a further look at those, via an i2cdump I get ..

root@beaglebone:~# i2cdump -y 1 0x62
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
10: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
20: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
30: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
40: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
50: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
60: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
70: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
80: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
90: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
a0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
b0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
c0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
d0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
e0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
f0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX

root@beaglebone:~# i2cdump -y 1 0x68
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 85 7d 83 50 df 0e 01 26 f9 97 04 d6 28 71 71 95 ?}?P???&????(qq?
10: 53 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 S...............
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
60: 00 00 00 00 00 00 00 00 00 00 00 40 00 00 00 00 ...........@....
70: 00 00 00 00 00 68 00 00 00 00 00 00 00 00 00 00 .....h..........
80: 85 7d 83 50 df 0e 01 26 f9 97 04 d6 28 71 71 95 ?}?P???&????(qq?
90: 53 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 S...............
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
e0: 00 00 00 00 00 00 00 00 00 00 00 40 00 00 00 00 ...........@....
f0: 00 00 00 00 00 68 00 00 00 00 00 00 00 00 00 00 .....h..........

my questions

* what are the 2 x devices? and why is one showing no data?
* is how to get to the OBD information? Is there any documentation / data sheet on the obd-ii adaptor? The i2cdump on the 0x68 address doesn't appear to be OBD information, or at least it doesn't change as events happen in the car.

Any help or pointers would be appreciated

thanks
e

[stanley]

Yes there are 2 devices one for OBD (addr 0x62) and one is MEMS (MPU-6050, addr 0x68). For writing your own code to communicate with them, please refer to the Arduino library sketches here:
https://github.com/stanleyhuangyc/ArduinoOBD/