Posted on March 01, 2017 at 18:26 I want to refactor this code from Betaflight
/external-link.jspa?url=https%3A%2F%2Fgithub.com%2Fcleanflight%2Fcleanflight%2Fblob%2Ffd1d8d532e8a21fec0b044e984f465b81f4cbed1%2Fsrc%2Fmain%2Fdrivers%2Fpwm_output_stm32f7xx.c
. It is to control brushless motors using a new digital protocol known as Dshot, which replaces PWM for escs for quadcopters etc. I want to use it for my robot for Piwars 2017.
The function that I am having problems understanding is the pwmDigitalMotorHardwareConfig . It is programmed in a generic way but I only need to use the dshot 1200 protocol, for four motors and one Nucleo board(f767zi at the moment)How do I start to understand what is going with regards to the timers, PWM and DMA so that I can modify it for my own needs ?
void
pwmDigitalMotorHardwareConfig
(
const
timerHardware_t *timerHardware,
uint8_t
motorIndex, motorPwmProtocolTypes_e pwmProtocolType,
uint8_t
output)
{
motorDmaOutput_t *
const
motor = &dmaMotors[motorIndex];
motor->timerHardware = timerHardware;
TIM_TypeDef *timer = timerHardware->tim;
const
IO_t motorIO =
IOGetByTag
(timerHardware->tag);
const
uint8_t
timerIndex =
getTimerIndex
(timer);
const
bool
configureTimer = (timerIndex == dmaMotorTimerCount-
1
);
IOInit
(motorIO, OWNER_MOTOR,
RESOURCE_INDEX
(motorIndex));
IOConfigGPIOAF
(motorIO,
IO_CONFIG
(GPIO_MODE_AF_PP, GPIO_SPEED_FREQ_VERY_HIGH, GPIO_PULLUP), timerHardware->alternateFunction);
__DMA1_CLK_ENABLE
();
if
(configureTimer) {
RCC_ClockCmd
(
timerRCC
(timer), ENABLE);
motor->TimHandle.
Instance
= timerHardware->tim;
motor->TimHandle.
Init
.
Prescaler
= (SystemCoreClock /
timerClockDivisor
(timer) /
getDshotHz
(pwmProtocolType)) -
1
;;
motor->TimHandle.
Init
.
Period
= MOTOR_BITLENGTH;
motor->TimHandle.
Init
.
RepetitionCounter
=
0
;
motor->TimHandle.
Init
.
ClockDivision
= TIM_CLOCKDIVISION_DIV1;
motor->TimHandle.
Init
.
CounterMode
= TIM_COUNTERMODE_UP;
if
(
HAL_TIM_PWM_Init
(&motor->TimHandle) != HAL_OK)
{
/*
Initialization Error
*/
return
;
}
}
else
{
motor->TimHandle = dmaMotors[timerIndex].
TimHandle
;
}
motor->timerDmaSource =
timerDmaSource
(timerHardware->channel);
dmaMotorTimers[timerIndex].
timerDmaSources
|= motor->timerDmaSource;
/*
Set the parameters to be configured
*/
motor->hdma_tim.
Init
.
Channel
= timerHardware->dmaChannel;
motor->hdma_tim.
Init
.
Direction
= DMA_MEMORY_TO_PERIPH;
motor->hdma_tim.
Init
.
PeriphInc
= DMA_PINC_DISABLE;
motor->hdma_tim.
Init
.
MemInc
= DMA_MINC_ENABLE;
motor->hdma_tim.
Init
.
PeriphDataAlignment
= DMA_PDATAALIGN_WORD;
motor->hdma_tim.
Init
.
MemDataAlignment
= DMA_MDATAALIGN_WORD;
motor->hdma_tim.
Init
.
Mode
= DMA_NORMAL;
motor->hdma_tim.
Init
.
Priority
= DMA_PRIORITY_HIGH;
motor->hdma_tim.
Init
.
FIFOMode
= DMA_FIFOMODE_DISABLE;
motor->hdma_tim.
Init
.
FIFOThreshold
= DMA_FIFO_THRESHOLD_FULL;
motor->hdma_tim.
Init
.
MemBurst
= DMA_MBURST_SINGLE;
motor->hdma_tim.
Init
.
PeriphBurst
= DMA_PBURST_SINGLE;
/*
Set hdma_tim instance
*/
if
(timerHardware->dmaStream ==
NULL
)
{
/*
Initialization Error
*/
return
;
}
motor->hdma_tim.
Instance
= timerHardware->dmaStream;
/*
Link hdma_tim to hdma[x] (channelx)
*/
__HAL_LINKDMA
(&motor->TimHandle, hdma[motor->timerDmaSource], motor->hdma_tim);
dmaInit
(timerHardware->dmaIrqHandler, OWNER_MOTOR,
RESOURCE_INDEX
(motorIndex));
/*
Initialize TIMx DMA handle
*/
if
(
HAL_DMA_Init
(motor->TimHandle.
hdma
[motor->timerDmaSource]) != HAL_OK)
{
/*
Initialization Error
*/
return
;
}
TIM_OC_InitTypeDef TIM_OCInitStructure;
/*
PWM1 Mode configuration: Channel1
*/
TIM_OCInitStructure.
OCMode
= TIM_OCMODE_PWM1;
if
(output & TIMER_OUTPUT_N_CHANNEL) {
TIM_OCInitStructure.
OCNPolarity
= (output & TIMER_OUTPUT_INVERTED) ? TIM_OCNPOLARITY_HIGH : TIM_OCNPOLARITY_LOW;
TIM_OCInitStructure.
OCNIdleState
= TIM_OCNIDLESTATE_RESET;
}
else
{
TIM_OCInitStructure.
OCPolarity
= (output & TIMER_OUTPUT_INVERTED) ? TIM_OCPOLARITY_LOW : TIM_OCPOLARITY_HIGH;
TIM_OCInitStructure.
OCIdleState
= TIM_OCIDLESTATE_SET;
}
TIM_OCInitStructure.
OCFastMode
= TIM_OCFAST_DISABLE;
TIM_OCInitStructure.
Pulse
=
0
;
if
(
HAL_TIM_PWM_ConfigChannel
(&motor->TimHandle, &TIM_OCInitStructure, motor->timerHardware->channel) != HAL_OK)
{
/*
Configuration Error
*/
return
;
}
}
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