ChibiOS Free Embedded RTOS

Posted: **Tue Jul 15, 2014 4:43 pm**

hi
I'm testing testhal, I2C example on STM32F4-Discovery.
I've noticed that in this example board.h is NONSTANDARD_STM32F4_BARTHESS1 and not ST_STM32F4_DISCOVERY.
When I've changed board.h to DISCOVERY, I2CD2 was not working. Then I realized that GPIOB_CLK_IN, GPIOB_SDA are connected to (PIN10,PIN9), while according to the datasheet it should be connected as follow: GPIOB_CLK_IN, GPIOB_SDA (PIN10,PIN11). BTW, on NONSTANDARD_STM32F4_BARTHESS1 I2CD2 are set according to the datasheet - please note.
my problem now is that I cannot change I2C speed or dutycycle: when I change default I2CConfig values: 400KHz or FAST_DUTY_CYCLE_2 I don't get any I2C output signal (I'm checking with both scope and logic analyzer).
any idea? thanks

Posted: **Tue Jul 15, 2014 5:32 pm**

I cannot test that scenario, are you sure you are specifying valid values? there are restrictions according to the Reference Manual.

Giovanni

Posted: **Tue Jul 15, 2014 6:23 pm**

I'm using I2C no problem on a Discovery F4 with the following configuration:

Code: Select all

static I2CConfig i2cfg1 = {
     OPMODE_I2C,
     100000,
     STD_DUTY_CYCLE
};

Posted: **Wed Jul 16, 2014 7:29 am**

Thanks a lot for your quick reply...
from any reason this is the only configuration that is working for me:

Code: Select all

static const I2CConfig i2cfg2 = {
    OPMODE_I2C,
    400000,
    FAST_DUTY_CYCLE_2,
};

any chnge in speed or dutycycle is not working. same resaults on I2CD1 or I2CD2...
while testing I2C with my own code, without ChibiOs I'm getting 100KHz I2C.

Posted: **Wed Jul 16, 2014 7:41 am**

Are I/Os programmed correcty?

Giovanni

Posted: **Thu Jul 17, 2014 6:06 am**

hi,

I2C I/O settings is as follow:

Code: Select all

  palSetPadMode(GPIOB, 10, PAL_MODE_ALTERNATE(4) | PAL_STM32_OTYPE_OPENDRAIN);   /* SCL */
  palSetPadMode(GPIOB, 11, PAL_MODE_ALTERNATE(4) | PAL_STM32_OTYPE_OPENDRAIN);   /* SDA */

After some more speed & duty-cycle combination checking, the followings are working:
400kKHz+FAST_DUTY_CYCLE_2, 100KHz+STD_DUTY_CYCLE - WORKING
400kKHz+STD_DUTY_CYCLE, 100KHz+FAST_DUTY_CYCLE_2 - NOT WORKING

For me it's OK now, but it would be nice to know if others see the same results and to understand why.

Thanks for the help!

ChibiOS Free Embedded RTOS

Problem with changing I2C speed or dutycycle

Problem with changing I2C speed or dutycycle

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Re: Problem with changing I2C speed or dutycycle