PWM LED driving

Change-Id: Ic3eb3c13e5a0f35e13caf96039304647b2363bd2

ion/include/ion/led.h

@@ -0,0 +1,20 @@
+#ifndef ION_LED_H
+#define ION_LED_H
+
+/* ION abstracts pushing pixels to the screen.
+ *
+ * There could be a single entry point, set_pixel, but setting pixels one by one
+ * incurs quite a large overhead because you need to send the coordinate of each
+ * pixel to the screen.
+ *
+ * Many displays support sending contiguous pixels without having to repeat the
+ * pixel coordinates every time. We're therefore leveraging this capability
+ * which results in a very consequent speedup (up to ~10x faster). */
+
+#include <stdint.h>
+
+typedef uint16_t ion_color_t;
+
+void ion_led_set_color(ion_color_t color);
+
+#endif

ion/src/device/Makefile

@@ -1,5 +1,5 @@
 include ion/src/device/boot/Makefile
-objs += $(addprefix ion/src/device/, init.o heap.o)
+objs += $(addprefix ion/src/device/, init.o heap.o led.o)
 objs += $(addprefix ion/src/device/display/,\
   display.o\
   gpio.o\

ion/src/device/init.c

@@ -19,6 +19,7 @@ void enable_fpu() {
 void init_platform() {
   enable_fpu();
   init_keyboard();
+  ion_led_init();
   init_display();
 }
 

ion/src/device/led.c

@@ -0,0 +1,89 @@
+#include <ion/led.h>
+#include "registers/registers.h"
+
+/* Pin used :
+ * PA8 -  Red LED - TIM1_CH1
+ * PA9 -  Green LED - TIM1_CH2
+ * PA10 - Blue LED  -TIM1_CH3
+ */
+
+void sleep() {
+  for (volatile int i=0;i<100000; i++) {
+  }
+}
+
+void ion_led_gpio_init() {
+  // We are using GPIOA, which live on the AHB1 bus. Let's enable its clock.
+  RCC_AHB1ENR |= GPIOAEN;
+
+#if 0
+
+  for (int i=8; i<=8; i++) {
+    REGISTER_SET_VALUE(GPIO_MODER(GPIOA), MODER(i), GPIO_MODE_OUTPUT);
+  }
+  char value = 1;
+  while (1) {
+    value = !value;
+    for (int i=8; i<=10; i++) {
+      REGISTER_SET_VALUE(GPIO_ODR(GPIOA), ODR(i), value);
+    }
+    for (volatile int i=0; i<100000; i++) {
+    }
+  }
+#else
+
+  /* RED_LED(PA8), GREEN_LED(PA9), BLUE_LED(PA10) are driven using a timer,
+   * which is an alternate function. */
+  REGISTER_SET_VALUE(GPIO_MODER(GPIOA), MODER(8), GPIO_MODE_ALTERNATE_FUNCTION);
+  REGISTER_SET_VALUE(GPIO_MODER(GPIOA), MODER(9), GPIO_MODE_ALTERNATE_FUNCTION);
+  REGISTER_SET_VALUE(GPIO_MODER(GPIOA), MODER(10), GPIO_MODE_ALTERNATE_FUNCTION);
+
+  /* More precisely, we will use AF01, which maps PA8 to TIM1_CH1, PA9 to
+   * TIM1_CH2 and PA10 to TIM1_CH3. */
+  REGISTER_SET_VALUE(GPIO_AFR(GPIOA, 8), AFR(8), 1);
+  REGISTER_SET_VALUE(GPIO_AFR(GPIOA, 9), AFR(9), 1);
+  REGISTER_SET_VALUE(GPIO_AFR(GPIOA, 10), AFR(10), 1);
+#endif
+}
+
+void ion_led_timer_init() {
+  /* TIM1 lives on the APB2 bus. Let's enable its clock. */
+  RCC_APB2ENR |= TIM1EN;
+  TIM_PSC(TIM1) = 1000;
+
+  /* Pulse width modulation mode allows you to generate a signal with a
+   * frequency determined by the value of the TIMx_ARR register and a duty cycle
+   * determined by the value of the TIMx_CCRx register. */
+  TIM_ARR(TIM1) = 40000;
+  TIM_CCR1(TIM1) = 20000;
+  TIM_CCR2(TIM1) = 20000;
+
+
+  // Set Channel 1 as output, PWM mode 1
+  REGISTER_SET_VALUE(TIM_CCMR1(TIM1), TIM_OC1M, 6);
+  // Set Channel 2 as output, PWM mode 2
+  REGISTER_SET_VALUE(TIM_CCMR1(TIM1), TIM_OC2M, 6);
+  //REGISTER_SET_VALUE(TIM_CCMR2(TIM1), TIM_OC3M, 6);
+
+  // Output preload enable for channel 1 and 2
+  TIM_CCMR1(TIM1) |= (TIM_OC1PE | TIM_OC2PE);
+
+  // Auto-reload preload enable
+  TIM_CR1(TIM1) |= TIM_ARPE;
+
+  // Enable Capture/Compare channel 1 and channel 2
+  TIM_CCER(TIM1) |= (TIM_CC1E | TIM_CC2E);
+
+  TIM_BDTR(TIM1) |= (TIM_MOE);
+
+  TIM_CR1(TIM1) |= (TIM_CEN); // Enable the counter
+}
+
+void ion_led_init() {
+  ion_led_gpio_init();
+  ion_led_timer_init();
+}
+
+
+void ion_led_set_color(ion_color_t color) {
+}

ion/src/device/registers/registers.h

@@ -25,4 +25,5 @@
 #include "spi.h"
 #include "dma.h"
 #include "cm4.h"
+#include "tim.h"
 //#include "ltdc.h"

ion/src/device/registers/tim.h

@@ -0,0 +1,85 @@
+#ifndef STM32_REGISTERS_TIM_H
+#define STM32_REGISTERS_TIM_H 1
+
+#define TIM1_BASE 0x40010000
+#define TIM2_BASE 0x40000000
+#define TIM3_BASE 0x40000400
+#define TIM4_BASE 0x40000800
+
+#define TIM_REGISTER_AT(timer,offset) (*(volatile uint16_t *)(timer##_BASE+offset))
+
+// TIM control registers 1
+
+#define TIM_CR1(timer) TIM_REGISTER_AT(timer, 0x00)
+
+#define TIM_CEN (1<<0)
+#define TIM_UDIS (1<<1)
+#define TIM_URS (1<<2)
+#define TIM_OPM (1<<3)
+#define TIM_DIR (1<<4)
+//#define TIM_CMS
+#define TIM_ARPE (1<<7)
+#define TIM_CKD_1 0
+#define TIM_CKD_2 1
+#define TIM_CKD_4 2
+
+// TIM control registers 2
+
+#define TIM_CR2(timer) TIM_REGISTER_AT(timer, 0x04)
+
+#define TIM_CDDS (1<<3)
+#define TIM_MMS_RESET 0
+#define TIM_MMS_ENABLE 1
+#define TIM_MMS_UPDATE 2
+#define TIM_MMS_COMPARE_PULSE 3
+#define TIM_TI1S (1<<7)
+
+// TIM capture/compare mode register 1
+
+#define TIM_CCMR1(timer) TIM_REGISTER_AT(timer, 0x18)
+
+//#define LOW_BIT_TIM_CC1S 0
+//#define HIGH_BIT_TIM_CC1S 1
+#define TIM_OC1PE (1<<3)
+#define LOW_BIT_TIM_OC1M 4
+#define HIGH_BIT_TIM_OC1M 6
+#define TIM_OC2PE (1<<11)
+#define LOW_BIT_TIM_OC2M 12
+#define HIGH_BIT_TIM_OC2M 14
+
+#define TIM_CCMR2(timer) TIM_REGISTER_AT(timer, 0x1C)
+
+#define LOW_BIT_TIM_OC3M 4
+#define HIGH_BIT_TIM_OC3M 6
+
+// TIM capture/compare enable register
+#define TIM_CCER(timer) TIM_REGISTER_AT(timer, 0x20)
+
+#define TIM_CC1E (1<<0)
+#define TIM_CC1P (1<<1)
+#define TIM_CC1NE (1<<2)
+#define TIM_CC2E (1<<4)
+#define TIM_CC2P (1<<5)
+#define TIM_CC2NE (1<<6)
+
+#define TIM_CNT(timer) TIM_REGISTER_AT(timer, 0x24)
+#define TIM_PSC(timer) TIM_REGISTER_AT(timer, 0x28)
+
+// TIM auto-reload register
+#define TIM_ARR(timer) TIM_REGISTER_AT(timer, 0x2C)
+
+// TIM capture/compare register 1
+#define TIM_CCR1(timer) TIM_REGISTER_AT(timer, 0x34)
+
+// TIM capture/compare register 2
+#define TIM_CCR2(timer) TIM_REGISTER_AT(timer, 0x38)
+
+
+// TIM break and dead-time register
+
+#define TIM_BDTR(timer) TIM_REGISTER_AT(timer, 0x44)
+
+
+#define TIM_MOE (1<<15)
+
+#endif