ChibiOS Free Embedded RTOS

Posted: **Sun Dec 30, 2012 10:24 am**

Hi,

I have bought very basic board with STM32F103C8T6 uC.
I am trying to make the icu to work w/o success.
The ICU seems not to start as the line is low after starting and enabling the ICU.
Very similar code works well on STM32F4 board.

Code: Select all

   DHT_icucfg.mode = ICU_INPUT_ACTIVE_HIGH;
   DHT_icucfg.frequency = DHT_ICU_FREQ;
   DHT_icucfg.width_cb = DHT_icuwidthcb;
   DHT_icucfg.period_cb = DHT_icuperiodcb;
   DHT_icucfg.overflow_cb = NULL;
   DHT_icucfg.channel = ICU_CHANNEL_1;

   DHT1122_data data;

   // REQUEST SAMPLE
   palSetPadMode(GPIOB, 6, PAL_MODE_OUTPUT_OPENDRAIN);
   palWritePad(GPIOB, 6, PAL_LOW);
   chThdSleepMilliseconds(20);

   palSetPadMode(GPIOB, 6, PAL_MODE_STM32_ALTERNATE_PUSHPULL);
   icuStart(&ICUD4, &DHT_icucfg);
   icuEnable(&ICUD4);

The code suppose to communicate with DHT22 sensor.

The B6 alternate function is default I2C1_SCL/TIM4_CH1.
I am not using I2C.

As I said before, the B6 line is low no matter to ICU_INPUT_ACTIVE_HIGH.

Should I do any splecial remaping or sth.?

Thanks in advance.

Greetings
Piotr Klimczak

Posted: **Sun Dec 30, 2012 10:48 am**

If GPIOB 6 is supposed to be an ICU input then you should program it as input, not output.

Giovanni

Posted: **Sun Dec 30, 2012 12:19 pm**

Hi Giovanni!

Thanks for the answer.
The DHT22 needs a little trick to start transmittion.
It needs the line to be set HIGH to LOW for 20ms then back to HIGH.

HIGH to LOW is done by:

Code: Select all

   palSetPadMode(GPIOB, 6, PAL_MODE_OUTPUT_OPENDRAIN);
   palWritePad(GPIOB, 6, PAL_LOW);
   chThdSleepMilliseconds(20);

Then after 20ms:

Code: Select all

   palSetPadMode(GPIOB, 6, PAL_MODE_STM32_ALTERNATE_PUSHPULL);
   icuStart(&ICUD4, &DHT_icucfg);
   icuEnable(&ICUD4);

So the line is set as INPUT as I believe. Am I right?
Same code works on STM32F4, so what is wrong?

Please note that I have tried different TIMs, Channels, lines etc.

Thanks in advance!

Piotr

Posted: **Sun Dec 30, 2012 12:26 pm**

I have forgotten to say- I am using latest trunk.

Piotr

Posted: **Sun Dec 30, 2012 12:53 pm**

The F4 has a different GPIO, the F1 requires that the alternate inputs to be normal inputs but I think that also output open drain should work. Just keep it PAL_MODE_OUTPUT_OPENDRAIN set to high.

Giovanni

Posted: **Tue Jan 01, 2013 10:36 pm**

Thanks a lot Giovanni!

As always you ware right!

Everything works well now!

BTW. Happy new year!

Greetings,
Piotr

ChibiOS Free Embedded RTOS

STM32F103 ICU not starting keeping the line low

STM32F103 ICU not starting keeping the line low

Re: STM32F103 ICU not starting keeping the line low

Re: STM32F103 ICU not starting keeping the line low

Re: STM32F103 ICU not starting keeping the line low

Re: STM32F103 ICU not starting keeping the line low

Re: STM32F103 ICU not starting keeping the line low