070RB hangs when reading a register

mike louaillier · ‎2017-03-23

Posted on March 24, 2017 at 07:20

Hello can someone help me with this? it's a simple ADC conversion that hangs on line 8. i don't see how this is possible.

1 ADC1->CR |= (uint32_t)ADC_CR_ADSTART; // start first conversion

2 count = 0;

3 while(((ADC1->ISR & ADC_ISR_EOC) == (uint32_t)reset) && (count < timeout)) // wait for end of conversion

4 { count++; }

5 capVL = (uint16_t)ADC1->DR; // read value

6 ADC1->CR |= (uint32_t)ADC_CR_ADSTART; // start second conversion

7 count = 0;

8 while(((ADC1->ISR & ADC_ISR_EOC) == (uint32_t)reset) && (count < timeout)) // wait for end of conversion

9 { count++; }

10// while(count < timeout) count++;

11 capVH = (uint16_t)ADC1->DR; // read value

if i conceal lines 8 & 9 and expose line 10, like so:

8// while((ADC1->ISR & ADC_ISR_EOC) == (uint32_t)reset && (count < timeout)) // wait for end of conversion

9// { count++; }

10 while(count < timeout) count++;

then it runs fine. dunno why the ADC operation on line 6 isn't working, but working or not, it should still timeout and keep going. it's not supposed to just hang. WTF? it's just reading a register.

#register-access

waclawek.jan · ‎2017-03-24

Posted on March 24, 2017 at 08:45

Is the count variable qualified as volatile?

How do you know the program hangs on line 8? What is the content of ADC registers when it hangs?

JW

mike louaillier · ‎2017-03-24

Posted on March 25, 2017 at 01:07

ok i made it a volatile but it didn't seem to make a difference.

and maybe it's not line 8. but i do what i always do, disable lines 8 & 9 and run it again. if the code runs correctly the second time, then i figure line 8 is the culprit. i repeat the test once or twice more, run it with and without lines 8 & 9.

here's the register values:

thanx

S.Ma · ‎2017-03-25

Posted on March 25, 2017 at 15:37

Which device is used?

mike louaillier · ‎2017-03-25

Posted on March 25, 2017 at 18:57

it's a nucleo board with a stm32f070rb mcu

S.Ma · ‎2017-03-25

Posted on March 25, 2017 at 19:18

Just to make sure, try by replacing 'reset' by 0

mike louaillier · ‎2017-03-25

Posted on March 25, 2017 at 19:56

well yeah it couldn't hurt but now the IDE is not connecting to the board so if it ain't one thing it's another...

mike louaillier · ‎2017-03-25

Posted on March 26, 2017 at 04:22

well ok after 6 hours i got a new IDE and no it's still freezing at line 8

Jan Waclawek · ‎2017-03-26

Posted on March 26, 2017 at 08:43

Post a minimal but complete compilable example exhibiting the problem.

JW

mike louaillier · ‎2017-03-26

Posted on March 27, 2017 at 01:44

well it looks as though the problem spontaneously resolved. i Xed out the usb function and ran the program again. the problem went away. the program stopped hanging at the ADC routine. the usb, it seems, was interfering.

but then i re-included the usb function and now the ADC still works fine. since the problem won't happen now, i can never figure out what it was.

so the problem is resolved but never solved. i just hope it stays that way.

thanx Jan