[ell-i-developers] Re: PWM configuration
- From: Ivan Raul <supra.material@xxxxxxxxx>
- To: ell-i-developers@xxxxxxxxxxxxx
- Date: Fri, 24 Jan 2014 16:34:25 +0200
Ready, now the pwm output is working. The initialization of AF (Alternate
Function) registers of the GPIO is missing. It was done in the previous
runtime at the file:
https://github.com/Ell-i/Arduino/blob/ell-i/hardware/ell-i/stm32/variants/ellduino_stm32f051/stm32f051_init.c
For consulting the alternate functions and corresponding values for the AF
registers, the datasheet is necessary:
http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00039193.pdf(page
38 for the B port)
and the reference manual page 164 (
http://www.st.com/web/en/resource/technical/document/reference_manual/DM00031936.pdf
)
All the previous documents are linked through the wiki of the hackathon
repsitory:
https://github.com/Ell-i/Hackathon/wiki/Components-STM32F051
Pekka: What do you suggest as following step? I was planning first to make
the timer configured from initialization records, and then start porting
the AF default values to the gpio initialization.
With Warm Regards, Ivan Raul
On Fri, Jan 24, 2014 at 3:45 PM, Ivan Raul <supra.material@xxxxxxxxx> wrote:
> Good news,
>
> The timer is now running. The problem is between the timer ouptut and the
> pin, maybe the pin is not correctly activated as alternate function.
>
>
>
>
> With Warm Regards, Ivan Raul
>
>
> On Fri, Jan 24, 2014 at 2:43 PM, Ivan Raul <supra.material@xxxxxxxxx>wrote:
>
>> Great, I have been checking the old runtime, but didn't checked that
>> initialization code. I'll continue accordingly.
>>
>> With Warm Regards, Ivan Raul
>>
>>
>> On Fri, Jan 24, 2014 at 2:38 PM, Pekka Nikander <pekka.nikander@xxxxxx>wrote:
>>
>>> Hi Ivan,
>>>
>>> It may also be a good idea to have a look at the old runtime and the
>>> corresponding code there:
>>>
>>>
>>> https://github.com/Ell-i/Arduino/blob/ell-i/hardware/ell-i/stm32/variants/ellduino_stm32f051/stm32f051_init.c
>>>
>>> It is known to work there. Hence, everything that are direct copies are
>>> unlike to have bugs. The bugs are more likely to be either in the changed
>>> surrounding initialisation code, which was completely rewritten, or in the
>>> pin definitions.
>>>
>>> It may also be a good idea to start with a simpler timer, like TIM3 or
>>> TIM15.
>>>
>>> --Pekka
>>>
>>> On 2014-01-24, at 14:33 , Ivan Raul <supra.material@xxxxxxxxx> wrote:
>>>
>>> > Dear all.
>>> >
>>> > I've been working with the testing of the PWM at the new runtime
>>> (ell-i-new branch).
>>> >
>>> > After solving the addressing problem of:
>>> >
>>> > @ellduino_timer.c
>>> >
>>> > # define D16(p, r, v) [offsetof(p, r)/2] = { v }
>>> >
>>> > and reordering the declarations of the initialisation records:
>>> >
>>> > @arduelli_timer.h
>>> >
>>> > for obtaining the adequate order at the .hex file (shown by the nm
>>> command)
>>> >
>>> > @sketch.lst
>>> >
>>> > 080003dc <TIM2_RCC_INIT>:
>>> > 080003ec <TIM2_INIT1>:
>>> > 080003fc <TIM2_INIT>:
>>> >
>>> > the pwm still doesn't work.
>>> >
>>> > In particular, I'm playing with the B3 pin (pin 13 in arduino), that
>>> directly connects with the TIM2 Channel 2.
>>> >
>>> > I've tried to initialize the timer manually, accessing the registers
>>> directly.
>>> >
>>> > Some highlights are that the TIM2 doesn't have a BDTR register, that
>>> the initialization procedure tries to write. In the datasheet, it is
>>> regarded as reserved. That register has the offset 0x44, and is mainly used
>>> for advanced timers, like TIM1.
>>> >
>>> > Another interesting point is that TIM2 in particular is able to count
>>> in 32 bits. For that reason, the CNT, ARR, and CCRx registers are 32 bits.
>>> Regarding that, it is true that after the initialization with 16bits
>>> initialization routines, the ARR register does not have the desired value,
>>> as the MSB are loaded with garbage.
>>> >
>>> > For the reasons before, I tried to configure it by accessing the
>>> registers directly. I had have no success. Another interesting fact is that
>>> in the datasheet (reference manual) of the MCU (page 370), it is specified
>>> that for PWM mode an update should be generated to update the real
>>> registers (ARR), because it is double buffered.
>>> >
>>> > The update is generated by writing the EGR register:
>>> >
>>> > TIM2->EGR |= TIM_EGR_UG;
>>> >
>>> > Still, the system doesn't activate the timer. The counter stays at 0
>>> all the time.
>>> >
>>> > I will continue by isolating the code to try to activate the timer by
>>> hand, and then port that configuration to the initialization records.
>>> >
>>> >
>>> > With Warm Regards, Ivan Raul
>>>
>>>
>>>
>>
>
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