I'm giving number 2 a try first since its the quickest, I've cabled this
all up and booted both boards. I've load all the correct i2c modules,
however when I run the 'i2c-io 0x0b info' command I get the error,
# ./i2c-io 0x0b info
ERROR: I2cTransfer: ioctl failed: Remote I/O error (121)
ERROR: I2cReadBlock failed
ERROR: Unable to retrieve information from i2c address 0x0b
This error also shows up in the syslog at the same time,
Dec 31 16:26:59 gumstix user.warn kernel: i2c: error: exhausted retries
Dec 31 16:26:59 gumstix user.warn kernel: i2c: msg_num: 0 msg_idx: -2000
Dec 31 16:26:59 gumstix user.warn kernel: i2c: ICR: 000007e0 ISR: 00000002
Dec 31 16:26:59 gumstix user.warn kernel: i2c: log: [00000446:000007e0]
The red light on the robostix is blinking twice per second so I'd say
the right program is running
I connected pin12 on the robostix to the sda pin on the gpsstix with a
20k resister in between, and pin 16 on the robostix to the scl on the
gpsstix, also with the resister.
Since this hasn't been tested I wont spend too much time trying to get
it to work, but maybe I've made an obvious mistake I can't yet see.
Dave Hylands wrote:
> Hi John,
>> I have a connex 400xm and gpsstix board connected together, and was
>> hoping to be able to connect to the robostix over the i2c to be able to
>> read the adc's and control a couple of servos. Is the I2C broken out on
>> the robostix anywhere other than the hirose? I assume I'd have to
>> connect the I2C1-4 pins on the gpsstix board to 4 I2C pins on the
>> robostix, I'm just not sure which ones they are. Thanks in advance.
> You have a couple of options:
> 1 - The 3.3v to 5v converter for the robostix is the 8 pin chip that's
> closest to the hirose connector (and has 9515A printed on it). Pin 2
> is the 3.3v SCL, and pin 3 is the 3.3v SDA (Pin 1 is in the corner
> with the dot). You could solder wires onto there.
> 2 - The 5v SCL and SDA lines are available on the UARTS connector. Pin
> 12 is SDA and pin 16 is SCL. These are connected to +5 through a
> pullup resistor. If you were to connect a 20k resistor between each
> pin and ground, you should be able to connect the lines directly to
> the gumstix. I haven't tested this....
> 3 - You could use an external voltage converter to convert the +5 to 3.3v
> 4 - You could opt to use a different ATMega processor, like the
> ATMega8L, which is available in a DIP package. You could run the
> ATMega8L at 3.3v
> 5 - Similar to 4, but run it at 5v but pullup the SDA and SCL to 3.3v
> and connect them up directly to the gumstix.