Re: [Gumstix-users] Hacking the Robostix i2c-io program

[Dave H. <dhy...@gm...>]

Hi Marq,

> I am using the i2c-io program with good success so far but would like to take
> over the the I2C_IO_READ_REG_16 function. I have been looking at the various
> functions that call this and am not sure if I understand what
> I2C_IO_READ_REG_16 returns. It seems to me that it is returning the size of
> the information in bytes that it will sent via the i2c bus????  Also
> according to i2c.h it says that 32 bytes is the max data transfer, does this
> apply to I2C_IO_READ_REG_16? If not how much data can be sent during one
> transaction?

Yes - I2C_MAX_DATA_LEN (32) bytes is the max that can be returned for
any transaction. This is because there is an internal buffer allocated
of that length.

I2C_IO_READ_REG_16 uses what's know as a "Block Write - Block Read
Process Call with PEC" transaction. See page 32 of the SMBus
specification: <http://smbus.org/specs/smbus20.pdf>

The write data bytes consists of the contents of the
I2C_IO_ReadReg16_t structure, which is a single uint8_t containing the
address of the register to read.

The reply consists of a uint16_t (so a 2 byte reply).

> What I am trying to do is merge the RC-Test program into i2c-io. I have
> added the variables and functions that are required to calculate the
> incoming pulse. I have also included "RCInput.h" and added RCinput.o to my
> makefile. In the main functions I am executing the following lines of code:
> ----
> RCI_SetPulseCallback( PulseDetected );
> RCI_SetMissingPulseCallback( MissingPulse );
> RCI_Init();
> -----
> My problem is that that when I compile I get the following error:
> ----
> Compiling i2c-io.c ...
> cc1: warnings being treated as errors
> i2c-io.c:449: warning: 'PulseDetected' defined but not used
> i2c-io.c:483: warning: 'MissingPulse' defined but not used
> make: *** [i2c-io.o] Error 1
> ----
> Any ideas on what I might be missing that should be calling these functions?

I'd have to see your source file. The errors seem to imply that you've
defined a static function called PulseDetected but haven't actually
referenced it, which means that it thinks that you didn't actually
call RCI_SetPulseCallback( PulseDetected );

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/