I2C "SearchDevices on bus"

[tuxscreen]

Hi,

I have implemented some PreCheck function, where I check the availability of several chips on the bus. It serves mostly debug and programmers demands.

Code: Select all

   snip

data = 0;
for (i2c_addr = 1; i2c_addr < 0x7e; i2c_addr++)
 {
         res = I2CH_MasterTransmitTimeout(drvp, i2c_addr, &data, 1, NULL, 0, MS2ST(5));       
         if (res == RDY_OK)
            my_printf("%s: Device     at %02x\n", __func__, i2c_addr);
        else
            my_printf("%s: Device NOT at %02x\n", __func__, i2c_addr);
}


The code works perfectly for several devices I had in the past.

Now I have some new Chip, a charger controller. This chip has not all registers as writeable, only very selected regs are readable, some are writable.

If I run the quoted code on this chip, Chibi does not see it, because first it transfers the i2c-address (this is ack'd as I see on the oszi) and afterwards the register is written but this sub-Transaction is not ack'd by the charger-controller.
After all the function fails.

How can I get Chibi to only set the address, and return the result to me?
I also tried to set tx_bytes to 0, does not work?

BR
Marc

[Giovanni]

Hi,

Have you tired the i2CMasterReceive() function? I am not sure it would work because just sending the address is something I never seen.

Giovanni

[tuxscreen]

Hi Giovanni,

yes, I tried the Receive function, too. Out of my perspective, it just hangs, if you set rx_bytes to 0.

You are completely right. The only case where you Need this, is if you check the Hardware on the bus.

It's like:
see http://www.lm-sensors.org/wiki/man/i2cdetect or here: http://www.lm-sensors.org/browser/i2c-t ... 2cdetect.c

I have a test setup where I have connected a raspberry pi and a STM32 w/ Chibi to the same sensor board. If there are problems I also check if the Problem is still there if only one master is connected.

With the RaspberryPi I see all three devices on my board, with Chibi I see only one.

There are several Solutions
one is to have an API (just like in CMSIS), where you can do such stuff without DMA
second would be to have just such a Routine like i2cdetect
third would to pimp the i2c irq to handle such a mode, e.g. an I2C_ADDR_ONLY flag or a handling for rx_bytes && tx_bytes are 0.

What do you think?

BR
Marc

[Giovanni]

You may propose a patch. Putting counters to zero looks like the less disruptive.

Giovanni

[crispus]

I know this thread is old, but I kinda got around it by restarting the i2c driver:

Code: Select all

       i2cStop(cpuI2C);
       i2cStart(cpuI2C, &cpuI2cCfg);
       msg_t ret = i2cMasterTransmitTimeout(cpuI2C, addr, tx_buffer, 1,
                rx_buffer, 0, TIME_MS2I(10));