Cooling fan PWM control (#92)

* Starting fan timer init

* Pushing init function

* Starting tach

* Setting fan speed is working, tach is not

* Messing around with prescalar and auto reload

* Second fan tach

* I think I have the tach working now

* RPM calculation should now be correct

* Pushing power settings

* Adding extra functions

* Only setting up PWM control for PR, no tach

source/pdu/fan_control/fan_control.c

@@ -0,0 +1,61 @@
+#include "fan_control.h"
+#include "common/phal_F4_F7/gpio/gpio.h"
+
+extern uint32_t APB1ClockRateHz;
+extern uint32_t APB2ClockRateHz;
+
+bool fanControlInit()
+{
+    RCC->APB2ENR |= RCC_APB2ENR_TIM1EN; // Enable clock to TIM1
+    FAN_PWM_TIM->CR1 &= ~TIM_CR1_CEN; // Disable counter (turn off timer)
+
+    /* Solving for PSC:
+     * PWMfreq = Fclk / ((ARR + 1) × (PSC + 1)).
+     *
+     * PWMfreq is known, and we are setting ARR to 99 for ease of calculations.
+     *
+     * Therefore we solve for the below formula for the desired PSC based on the
+     * necessary PWMfreq specified by the fan vendor.
+    */
+
+    FAN_PWM_TIM->ARR = 100 - 1; // Using this for ease of calculations
+
+    FAN_PWM_TIM->PSC = (APB2ClockRateHz / (PWM_FREQUENCY_HZ * (FAN_PWM_TIM -> ARR + 1))) - 1;
+
+    FAN_PWM_TIM->CCR1 = 0; // Start with it off
+    FAN_PWM_TIM->CCR2 = 0; // Start with it off
+
+    // Set PWM mode 1 (active while CNT <= CCR1)
+    FAN_PWM_TIM->CCMR1 &= ~TIM_CCMR1_OC1M;
+    FAN_PWM_TIM->CCMR1 &= ~TIM_CCMR1_OC2M;
+    FAN_PWM_TIM->CCMR1 |= TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1M_1; // PWM Mode 1 ch1
+    FAN_PWM_TIM->CCMR1 |= TIM_CCMR1_OC2M_2 | TIM_CCMR1_OC2M_1; // PWM Mode 1 ch2
+    FAN_PWM_TIM->CCMR1 |= TIM_CCMR1_OC2PE |TIM_CCMR1_OC1PE; // Enable preload register ch1 & ch2
+
+    FAN_PWM_TIM->CCER |= TIM_CCER_CC2E | TIM_CCER_CC1E; // Enable output compare 1 & 2 
+
+    FAN_PWM_TIM->BDTR |= TIM_BDTR_MOE; // Enable main output
+
+    FAN_PWM_TIM->CR1 &= ~TIM_CR1_DIR; // Set to upcounting mode
+    FAN_PWM_TIM->CR1 |= TIM_CR1_ARPE; // Necessary in upcounting mode
+
+    FAN_PWM_TIM->CR1 |= TIM_CR1_CEN; // Enable counter (turn on timer)
+
+    FAN_PWM_TIM->CR1 |= TIM_CR1_CEN; // Enable FAN_PWM_TIM
+
+    return true;
+}
+
+// This speed will be between 0-100%
+void setFan1Speed(uint8_t fan_speed)
+{
+    // Duty cycle is (CCR1 / ARR)%. So CCR1 = (ARR / duty cycle)
+    FAN_PWM_TIM->CCR1 = (FAN_PWM_TIM -> ARR + 1) * (fan_speed / 100.0);
+}
+
+// This speed will be between 0-100%
+void setFan2Speed(uint8_t fan_speed)
+{
+    // Duty cycle is (CCR1 / ARR)%. So CCR1 = (ARR / duty cycle)
+    FAN_PWM_TIM->CCR2 = (FAN_PWM_TIM -> ARR + 1) * (fan_speed / 100.0);
+}

source/pdu/fan_control/fan_control.h

@@ -0,0 +1,15 @@
+#ifndef _FAN_CONTROL_H_
+#define _FAN_CONTROL_H_
+
+#include <stdbool.h>
+#include "stm32f407xx.h"
+#include "main.h"
+
+#define PWM_FREQUENCY_HZ (25000) // PWM frequency to be 25kHz
+#define FAN_PWM_TIM (FAN_1_PWM_TIM) // Fan 1 and 2 user same timer
+
+bool fanControlInit();
+void setFan1Speed(uint8_t fan_speed);
+void setFan2Speed(uint8_t fan_speed);
+
+#endif // _FAN_CONTROL_H_