CSU Chico Tilt Rotor Flying Machine, (Programming and CPU, 3 of 3).

Patrick, Thu Mar 29 2012, 01:09AM

CSU Chico Tilt Rotor Flying Machine, (Programming and CPU, 3 of 3).

Related Web Sources:
Servo control using STM32VLDiscovery

I have 2 ESC's and 2 servos, all require the normal servo PWM. the ESC's at 50 Hz PRF, the servos at 300HZ PRF.

code from the above link im trying to figure out:
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// STM32 4-channel Servo Demo for 24 MHz VL Discovery - **link**

#include "stm32F10x.h"
#include "STM32vldiscovery.h"

/ ************************************************** ************************************/

void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);
void TIM3_Configuration(void);

/ ************************************************** ************************************/

volatile int servo_angle[4] = { 0, 0, 0, 0 }; // +/- 90 degrees, use floats for fractional

void TIM3_IRQHandler(void)
{
if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_Update);

// minimum high of 600 us for -90 degrees, with +90 degrees at 2400 us, 10 us per degree
// timer timebase set to us units to simplify the configuration/math

TIM3->CCR1 = 600 + ((servo_angle[0] + 90) * 10); // where angle is an int -90 to +90 degrees, PC.6
TIM3->CCR2 = 600 + ((servo_angle[1] + 90) * 10); // where angle is an int -90 to +90 degrees, PC.7
TIM3->CCR3 = 600 + ((servo_angle[2] + 90) * 10); // where angle is an int -90 to +90 degrees, PC.8
TIM3->CCR4 = 600 + ((servo_angle[3] + 90) * 10); // where angle is an int -90 to +90 degrees, PC.9
}
}

/ ************************************************** ************************************/

int main(void)
{
RCC_Configuration();

GPIO_Configuration();

NVIC_Configuration();

TIM3_Configuration();

while(1)
{
// Insert code here to stroke your servos
}
}

/ ************************************************** ************************************/

void RCC_Configuration(void)
{
// clock for GPIO and AFIO (Remap)

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO, ENABLE);

// clock for TIM3

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
}

/ ************************************************** ************************************/

void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;

/* Configure the NVIC Preemption Priority Bits */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

/* Enable the TIM3 Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}

/ ************************************************** ************************************/

void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

// PC.06 TIM3_CH1
// PC.07 TIM3_CH2
// PC.08 TIM3_CH3
// PC.09 TIM3_CH4

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_Init(GPIOC, &GPIO_InitStructure);

GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE); // Remap to get signal on PC.06-09
}

/ ************************************************** ************************************/

void TIM3_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

// Simplify the math here so TIM_Pulse has 1 us units

// Use (24-1) for VL @ 24 MHz
// Use (72-1) for STM32 @ 72 MHz

TIM_TimeBaseStructure.TIM_Prescaler = 24 - 1; // 24 MHz / 24 = 1 MHz

TIM_TimeBaseStructure.TIM_Period = 20000 - 1; // 1 MHz / 20000 = 50 Hz (20 ms)

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

// Set up 4 channel servo

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = 600 + 900; // 1500 us - Servo Top Centre

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OC1Init(TIM3, &TIM_OCInitStructure); // Channel 1 configuration = PC.06 TIM3_CH1
TIM_OC2Init(TIM3, &TIM_OCInitStructure); // Channel 2 configuration = PC.07 TIM3_CH2
TIM_OC3Init(TIM3, &TIM_OCInitStructure); // Channel 3 configuration = PC.08 TIM3_CH3
TIM_OC4Init(TIM3, &TIM_OCInitStructure); // Channel 4 configuration = PC.09 TIM3_CH4

// turning on TIM3 and PWM outputs

TIM_Cmd(TIM3, ENABLE);

TIM_CtrlPWMOutputs(TIM3, ENABLE);

// TIM IT enable
TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);
}

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more code shortly...