Date: Wed, 30 Apr 2014 19:49:24 -0400 From: Winston Smith <smith.winston.101@gmail.com> To: Rui Paulo <rpaulo@freebsd.org> Cc: freebsd-arm <freebsd-arm@freebsd.org>, Mark R V Murray <mark@grondar.org> Subject: Re: i2c on RPI-B not working Message-ID: <CADH-AwFDk2uzOcNQQx%2BL%2BHGBgc7vccQVXLta_g6D3HRHhZxYsQ@mail.gmail.com> In-Reply-To: <1CFC3564-65F0-4DC8-950C-3D53BBB2761C@FreeBSD.org> References: <93181B67-1944-4DDD-A595-455D2AE9B110@grondar.org> <1CFC3564-65F0-4DC8-950C-3D53BBB2761C@FreeBSD.org>
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On Tue, Apr 29, 2014 at 1:07 PM, Rui Paulo <rpaulo@freebsd.org> wrote: > This is because the controller doesn't support scanning. You need to write your own C program to issue iic ioctls for reading / writing to the i2c bus. I'm in the same process except on a BeagleBone Black (currently running 11-CURRENT). Running `i2c -sv` under `ktrace -t+`, it's returning: 956 i2c CALL ioctl(0x3,I2CRSTCARD,0xbffffcc8) 956 i2c RET ioctl 0 956 i2c CALL ioctl(0x3,I2CSTART,0xbffffcc8) 956 i2c RET ioctl -1 errno 6 Device not configured 956 i2c CALL ioctl(0x3,I2CSTOP,0xbffffcc8) 956 i2c RET ioctl -1 errno 22 Invalid argument I know from Linux on the BBB, that when you run `i2cdetect`, you need to specify the `-r` to use "read byte" commands to probe the i2c bus and indeed I've written i2c code previously using ioctl() with I2CRDWR. So I cobbled together a I2C bus scanner, i2cscan.c: http://pastebin.com/RxpRCyJU root@beaglebone:~ # ./i2cscan /dev/iic0 Checking device: /dev/iic0 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Hmmm ... on the BBB it's still not detecting anything; in fact according to `ktrace`, it seems to still return ENXIO (Device not configured): 988 i2cscan CALL ioctl(0x3,I2CRDWR,0xbffffc58) 988 i2cscan RET ioctl -1 errno 6 Device not configured Not entirely sure why it's not detecting anything since I *know* the BBB has an EEPROM at 0x50 on bus 0 (I2C0 @ 44e0b000), which according to ofwdump should be iic0: root@beaglebone:~ # ofwdump -a Node 0x38: Node 0xc4: am335x ... Node 0x1504: i2c@44e0b000 Node 0x1590: pmic@24 ... So: 1) Hopefully, you'll have more luck with the i2cscan.c tool I wrote than I did! 2) Does anyone know why I'm not detecting any i2c devices on the BBB? Thanks! -W
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