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-rw-r--r--00-hello/main.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/00-hello/main.c b/00-hello/main.c
new file mode 100644
index 0000000..fe2b9d5
--- /dev/null
+++ b/00-hello/main.c
@@ -0,0 +1,354 @@
+#define __IO volatile
+
+#include <stdint.h>
+#define RCC_BASE_2 0x40021000
+
+int main();
+void spin();
+
+/*
+ * Interrupt service routine handlers.
+ */
+const void* vectors[] __attribute__((section(".vectors"))) = {
+ (void*)0x2000c000, /* Top of stack at top of sram1. 48k */
+ main, /* Reset handler */
+ spin, /* NMI */
+ spin, /* Hard Fault */
+ spin, /* MemManage */
+ spin, /* BusFault */
+ spin, /* UsageFault */
+ spin, /* Reserved */
+ spin, /* Reserved */
+ spin, /* Reserved */
+ spin, /* Reserved */
+ spin, /* SVCall */
+ spin, /* Debug */
+ spin, /* Reserved */
+ spin, /* PendSV */
+ spin, /* SysTick */
+
+ /* External interrupt handlers follow */
+ spin, /* 0 WWDG */
+ spin, /* 1 PVD */
+ spin, /* 2 TAMP_SAMP */
+ spin, /* 3 RTC_WKUP */
+ spin, /* 4 FLASH */
+ spin, /* 5 RCC */
+ spin, /* 6 EXTI0 */
+ spin, /* 7 EXTI1 */
+ spin, /* 8 EXTI2 */
+ spin, /* 9 EXTI3 */
+ spin, /* 10 EXTI4 */
+ spin, /* 11 DMA_CH1 */
+ spin, /* 12 DMA_CH2 */
+ spin, /* 13 DMA_CH3 */
+ spin, /* 14 DMA_CH4 */
+ spin, /* 15 DMA_CH5 */
+ spin, /* 16 DMA_CH6 */
+ spin, /* 17 DMA_CH7 */
+ spin, /* 18 ADC1 */
+ spin, /* 19 CAN_TX */
+ spin, /* 20 CAN_RX0 */
+ spin, /* 21 CAN_RX1 */
+ spin, /* 22 CAN_SCE */
+ spin, /* 23 EXTI9_5 */
+ spin, /* 24 TIM1_BRK/TIM15 */
+ spin, /* 25 TIM1_UP/TIM16 */
+ spin, /* 26 TIM1_TRG_COM */
+ spin, /* 27 TIM1_CC */
+ spin, /* 28 TIM2 */
+ spin, /* 29 Reserved */
+ spin, /* 30 Reserved */
+ spin, /* 31 I2C1_EV */
+ spin, /* 32 I2C1_ER */
+ spin, /* 33 I2C2_EV */
+ spin, /* 34 I2C2_ER */
+ spin, /* 35 SPI1 */
+ spin, /* 36 SPI2 */
+ spin, /* 37 USART1 */
+ spin, /* 38 USART2 */
+ spin, /* 39 USART3 */
+ spin, /* 40 EXTI15_10 */
+ spin, /* 41 RTCAlarm */
+ spin, /* 42 Reserved */
+ spin, /* 43 Reserved */
+ spin, /* 44 Reserved */
+ spin, /* 45 Reserved */
+ spin, /* 46 Reserved */
+ spin, /* 47 Reserved */
+ spin, /* 48 Reserved */
+ spin, /* 49 SDMMC1 */
+ spin, /* 50 Reserved */
+ spin, /* 51 SPI3 */
+ spin, /* 52 Reserved */
+ spin, /* 53 Reserved */
+ spin, /* 54 TIM6_DACUNDER */
+ spin, /* 55 TIM7 */
+ spin, /* 56 DMA2_CH1 */
+ spin, /* 57 DMA2_CH2 */
+ spin, /* 58 DMA2_CH3 */
+ spin, /* 59 DMA2_CH4 */
+ spin, /* 60 DMA2_CH5 */
+ spin, /* 61 Reserved */
+ spin, /* 62 Reserved */
+ spin, /* 63 Reserved*/
+ spin, /* 64 COMP */
+ spin, /* 65 LPTIM1 */
+ spin, /* 66 LPTIM2 */
+ spin, /* 67 USB_FS */
+ spin, /* 68 DMA_CH6 */
+ spin, /* 69 DMA_CH7 */
+ spin, /* 70 LPUART1 */
+ spin, /* 71 QUADSPI */
+ spin, /* 72 I2C3_EV */
+ spin, /* 73 I2C3_ER */
+ spin, /* 74 SAI1 */
+ spin, /* 75 Reserved */
+ spin, /* 76 SWPMI1 */
+ spin, /* 77 TSC */
+ spin, /* 78 Reserved */
+ spin, /* 79 AES */
+ spin, /* 80 RNG */
+ spin, /* 81 FPU */
+ spin /* 82 CRS */
+};
+
+typedef struct {
+ __IO uint32_t value;
+} rcc_reg_t;
+
+#define RCC_AHB2ENR (*((__IO rcc_reg_t*)(RCC_BASE_2 + 0x4c)))
+
+typedef enum {
+ GPIO_PORT_A = 0,
+ GPIO_PORT_B = 1,
+ GPIO_PORT_C = 2,
+ GPIO_PORT_D = 3
+} gpio_port_number_t;
+
+void enable_gpio(gpio_port_number_t port)
+{
+ RCC_AHB2ENR.value |= 1 << port;
+}
+
+typedef enum {
+ PIN_0 = 0,
+ PIN_1 = 1,
+ PIN_2 = 2,
+ PIN_3 = 3,
+ PIN_4 = 4,
+ PIN_5 = 5,
+ PIN_6 = 6,
+ PIN_7 = 7,
+ PIN_8 = 8,
+ PIN_9 = 9,
+ PIN_10 = 10,
+ PIN_11 = 11,
+ PIN_12 = 12,
+ PIN_13 = 13,
+ PIN_14 = 14,
+ PIN_15 = 15
+} pin_t;
+
+typedef enum {
+ MODE_INPUT = 0,
+ MODE_OUTPUT = 1,
+ MODE_ALTERNATE = 2,
+ MODE_ANALOG = 3
+} pin_mode_t;
+
+/* GPIO port speed. */
+typedef enum {
+ SPEED_2MHZ = 0,
+ SPEED_10MHZ = 1,
+ SPEED_50MHZ = 3,
+} speed_t;
+
+/*
+ * Mode register. Input, output, alternate functiont or analog.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) mode_reg_t;
+
+/*
+ * Type register. Push/pull or open drain.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) type_reg_t;
+
+/*
+ * Speed register. Allows low, meduim, fast or high speed.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) speed_reg_t;
+
+/*
+ * Pull up/pull down register. Allows pull up, pull down, or no pull up or
+ * pull down.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) pull_reg_t;
+
+/*
+ * Stores the data for reading from the outside.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) input_data_reg_t;
+
+/*
+ * Stores the data for writing to the outside.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) output_data_reg_t;
+
+/*
+ * Writing a 1 to a bit in this register allows the user to set or reset a bit
+ * in the output data register.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) bit_set_reset_reg_t;
+
+/*
+ * Lock register. Allows the user to lock a pin so that its value cannot be
+ * changed.
+ */
+typedef struct {
+ __IO uint32_t value;
+} __attribute__((packed)) lock_reg_t;
+
+/*
+ * Alternate function.
+ */
+typedef struct {
+ __IO uint32_t value_high;
+ __IO uint32_t value_low;
+} __attribute__((packed)) alt_function_reg_t;
+
+/* Structure defining the layout of a GPIO port on the STM32L432. */
+typedef struct {
+ __IO mode_reg_t mode; /* Mode register */
+ __IO pull_reg_t pupd; /* Pull up/pull down/none register */
+ __IO speed_reg_t speed; /* Speed register */
+ __IO type_reg_t type; /* Type register */
+ __IO input_data_reg_t input; /* Input data register */
+ __IO output_data_reg_t output; /* Output data register */
+ __IO bit_set_reset_reg_t bsr; /* Bit set/reset register */
+ __IO lock_reg_t lock; /* Lock register */
+ __IO alt_function_reg_t altfn; /* Alternate function registers */
+} __attribute__((packed)) gpio_port_t;
+
+/*
+ * Defines for GPIO memory mapped addresses.
+ */
+#define GPIO_A (*((__IO gpio_port_t*)0x48000000))
+#define GPIO_B (*((__IO gpio_port_t*)0x48000400))
+#define GPIO_C (*((__IO gpio_port_t*)0x48000800))
+
+/*
+ * Delays for `delay` iterations.
+ */
+void delay(uint32_t delay)
+{
+ while (delay--) {
+ // Empty volatile assembly to keep the optimizer from getting
+ // rid of this loop entirely.
+ asm volatile("");
+ }
+}
+
+/*
+ * Sets the mode of a pin on a gpio port.
+ *
+ * gpio_port: the gpio port.
+ * pin: the number of the port;
+ * pin_mode: the mode of the pin. See pin_mode_t enum.
+ */
+void set_gpio_pin_mode(
+ __IO gpio_port_t* gpio_port, uint32_t pin, pin_mode_t pin_mode)
+{
+ gpio_port->mode.value &= ~(0x03 << pin * 2);
+ gpio_port->mode.value |= pin_mode << pin * 2;
+}
+
+/*
+ * Sets the value on an output GPIO pin.
+ *
+ * gpio_port: The gpio port.
+ * pin: the number of the pin to enable. Values 0-15
+ * val: 0 to set the gpio pin to low, non-zero to set to high.
+ */
+void set_gpio_pin(__IO gpio_port_t* gpio_port, uint32_t pin, int val)
+{
+ if (val) {
+ gpio_port->output.value |= 1 << pin;
+ } else {
+ gpio_port->output.value &= ~(1 << pin);
+ }
+}
+
+/* Main function. This gets executed from the interrupt vector defined above. */
+int main()
+{
+ /* Enable the GPIO port B. */
+ enable_gpio(GPIO_PORT_B);
+
+ /* Set pin 3 and pin 1 of GPIO_B to be an output pin. */
+ set_gpio_pin_mode(&GPIO_B, /* pin = */ 3, MODE_OUTPUT);
+ set_gpio_pin_mode(&GPIO_B, /* pin = */ 1, MODE_OUTPUT);
+
+ while (1) {
+ /* Set the GPIO pin to high. */
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 1);
+ set_gpio_pin(&GPIO_B, /* pin = */ 1, 0);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+
+ /* Set the GPIO pin to low. */
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 0);
+ set_gpio_pin(&GPIO_B, /* pin = */ 1, 1);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ delay(65535);
+ }
+}
+
+/*
+ * Does nothing ... forever.
+ */
+void spin()
+{
+ for (;;) {
+ /* Flash in a distinct pattern to know that something went wrong. */
+
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 0);
+ delay(100000);
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 1);
+ delay(100000);
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 0);
+ delay(100000);
+ set_gpio_pin(&GPIO_B, /* pin = */ 3, 1);
+ delay(500000);
+ }
+}
generated by cgit (git 2.34.1) at 2025-07-04 04:25:50 +0000