Hi, I'm trying to access data from a compass (CMPS03), the documentation of which being at <http://www.robot-electronics.co.uk/htm/cmps3doc.shtml>. This device is supposed to be at address 0xC0. I read at <http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2003-May/015484.html> that I should specify this as 0xC0 >> 1, which is 0x60 (0xC0 is clearly not supported anywhere anyway ;-). I have written a small program that should to that, but it doesn't work. Here is what I did. I attached it to my parallel port as in i2c-2.8.4/doc/i2c-pport. I loaded all the modules: pcffl root # lsmod Module Size Used by Tainted: P i2c-pport 1297 0 i2c-proc 6836 0 (unused) i2c-dev 4608 0 i2c-algo-bit 7720 0 [i2c-pport] i2c-core 15460 0 [i2c-proc i2c-dev i2c-algo-bit] and the parallel port is detected: pcffl root # cat /proc/bus/i2c i2c-0 i2c Primitive Parallel port adaptor Bit-shift algorithm My program is attached below: -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: compass2.c Url: http://lists.lm-sensors.org/pipermail/lm-sensors/attachments/20040405/6698ba46/attachment.c -------------- next part -------------- All it does is output 0, whatever register I read. Here is the output of i2cdetect and i2cdump: pcffl root # i2cdetect 0 WARNING! This program can confuse your I2C bus, cause data loss and worse! I will probe file /dev/i2c-0 You have five seconds to reconsider and press CTRL-C! 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: 00 01 02 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 78 79 7a 7b 7c 7d 7e 7f pcffl root # i2cdump 0 0x60 No size specified (using byte-data access) WARNING! This program can confuse your I2C bus, cause data loss and worse! I will probe file /dev/i2c-0, address 0x60, mode byte You have five seconds to reconsider and press CTRL-C! 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 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 00 00 00 00 00 ................ 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 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 00 00 00 00 00 ................ f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Now, the funny thing is that i2cdetect and i2cdump produce exactly the same thing whether or not my device is plugged in! One additional bit: pcffl root # cat /proc/sys/dev/parport/parport0/modes PCSPP,TRISTATE I hope someone can help me with that. Sorry for the long message. Cheers, Fred
