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Update example to use timers as well.

This example now exercises timers, EXTI, gpio, irqs as well as demonstrating printf.
It only needs a serial cable in addition to the 32L discovery board
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1 parent 20c2a14 commit b2fb224e51c65f0ff7f14ae17b3ae24042a28fd3 @karlp committed Nov 18, 2012
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29 examples/stm32/l1/stm32l-discovery/button-irq-printf/README
@@ -1,3 +1,32 @@
* Prints to the screen when the button is pushed/released (irq driven)
115200@8n1 console on PA2 (tx only)
+* uses basic timer 6 with overflows to generate a 1ms counter (not an ideal
+ use, but shows some api methods and can be demoed on the disco board)
+* uses basic timer 7 with the exti interrupts to do ghetto input capture.
+ Not as fast or precise as the real input capture modes, but can be used
+ on any gpio pin.
+
+example output:
+
+hi guys!
+TICK 0
+TICK 1
+TICK 2
+Pushed down!
+held: 443 ms
+Pushed down!
+TICK 3
+held: 217 ms
+Pushed down!
+held: 99 ms
+Pushed down!
+TICK 4
+held: 73 ms
+Pushed down!
+held: 60 ms
+TICK 5
+Pushed down!
+held: 98 ms
+Pushed down!
+
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205 examples/stm32/l1/stm32l-discovery/button-irq-printf/main.c
@@ -9,41 +9,53 @@
#include <libopencm3/stm32/l1/rcc.h>
#include <libopencm3/stm32/l1/gpio.h>
#include <libopencm3/stm32/exti.h>
+#include <libopencm3/stm32/timer.h>
#include <libopencm3/stm32/usart.h>
#include "syscfg.h"
static struct state_t state;
-void clock_setup(void) {
- /* Lots of things on all ports... */
- rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOAEN);
- rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOBEN);
+void clock_setup(void)
+{
+ rcc_clock_setup_pll(&clock_vrange1_config[CLOCK_VRANGE1_HSI_PLL_24MHZ]);
+ /* Lots of things on all ports... */
+ rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOAEN);
+ rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOBEN);
+
+ /* Enable clocks for USART2. */
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
+
+ /* And timers. */
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM6EN);
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM7EN);
- /* Enable clocks for USART2. */
- rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
}
-void gpio_setup(void) {
- gpio_mode_setup(LED_DISCO_GREEN_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_DISCO_GREEN_PIN);
+void gpio_setup(void)
+{
+ /* green led for ticking, blue for button feedback */
+ gpio_mode_setup(LED_DISCO_GREEN_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_DISCO_GREEN_PIN);
+ gpio_mode_setup(LED_DISCO_BLUE_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_DISCO_BLUE_PIN);
- /* Setup GPIO pins for USART2 transmit. */
- gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+ /* Setup GPIO pins for USART2 transmit. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
- /* Setup USART2 TX pin as alternate function. */
- gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+ /* Setup USART2 TX pin as alternate function. */
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
}
-void usart_setup(void) {
- usart_set_baudrate(USART_CONSOLE, 115200);
- usart_set_databits(USART_CONSOLE, 8);
- usart_set_stopbits(USART_CONSOLE, USART_STOPBITS_1);
- usart_set_mode(USART_CONSOLE, USART_MODE_TX);
- usart_set_parity(USART_CONSOLE, USART_PARITY_NONE);
- usart_set_flow_control(USART_CONSOLE, USART_FLOWCONTROL_NONE);
-
- /* Finally enable the USART. */
- usart_enable(USART_CONSOLE);
+void usart_setup(void)
+{
+ usart_set_baudrate(USART_CONSOLE, 115200);
+ usart_set_databits(USART_CONSOLE, 8);
+ usart_set_stopbits(USART_CONSOLE, USART_STOPBITS_1);
+ usart_set_mode(USART_CONSOLE, USART_MODE_TX);
+ usart_set_parity(USART_CONSOLE, USART_PARITY_NONE);
+ usart_set_flow_control(USART_CONSOLE, USART_FLOWCONTROL_NONE);
+
+ /* Finally enable the USART. */
+ usart_enable(USART_CONSOLE);
}
/**
@@ -53,65 +65,108 @@ void usart_setup(void) {
* @param len
* @return
*/
-int _write(int file, char *ptr, int len) {
- int i;
-
- if (file == STDOUT_FILENO || file == STDERR_FILENO) {
- for (i = 0; i < len; i++) {
- if (ptr[i] == '\n') {
- usart_send_blocking(USART_CONSOLE, '\r');
- }
- usart_send_blocking(USART_CONSOLE, ptr[i]);
- }
- return i;
- }
- errno = EIO;
- return -1;
+int _write(int file, char *ptr, int len)
+{
+ int i;
+
+ if (file == STDOUT_FILENO || file == STDERR_FILENO) {
+ for (i = 0; i < len; i++) {
+ if (ptr[i] == '\n') {
+ usart_send_blocking(USART_CONSOLE, '\r');
+ }
+ usart_send_blocking(USART_CONSOLE, ptr[i]);
+ }
+ return i;
+ }
+ errno = EIO;
+ return -1;
+}
+
+void BUTTON_DISCO_USER_isr(void)
+{
+ exti_reset_request(BUTTON_DISCO_USER_EXTI);
+ if (state.falling) {
+ gpio_clear(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
+ state.falling = false;
+ exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
+ unsigned int x = TIM_CNT(TIM7);
+ printf("held: %u ms\n", x);
+ } else {
+ gpio_set(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
+ printf("Pushed down!\n");
+ TIM_CNT(TIM7) = 0;
+ state.falling = true;
+ exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_FALLING);
+ }
+}
+
+static volatile int t6ovf = 0;
+
+void tim6_isr(void)
+{
+ TIM_SR(TIM6) &= ~TIM_SR_UIF;
+ if (t6ovf++ > 1000) {
+ printf("TICK %d\n", state.tickcount++);
+ t6ovf = 0;
+ gpio_toggle(LED_DISCO_GREEN_PORT, LED_DISCO_GREEN_PIN);
+ }
+}
+
+/*
+ * Another ms timer, this one used to generate an overflow interrupt at 1ms
+ * It is used to toggle leds and write tick counts
+ */
+void setup_tim6(void)
+{
+ timer_reset(TIM6);
+ // 24Mhz / 10khz -1.
+ timer_set_prescaler(TIM6, 2399); // 24Mhz/10000hz - 1
+ // 10khz for 10 ticks = 1 khz overflow = 1ms overflow interrupts
+ timer_set_period(TIM6, 10);
+
+ nvic_enable_irq(NVIC_TIM6_IRQ);
+ timer_enable_update_event(TIM6); // default at reset!
+ timer_enable_irq(TIM6, TIM_DIER_UIE);
+ timer_enable_counter(TIM6);
}
-void BUTTON_DISCO_USER_isr(void) {
- exti_reset_request(BUTTON_DISCO_USER_EXTI);
- if (state.falling) {
- state.falling = false;
- exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
- // ILOG("fell: %d\n", TIM_CNT(TIM7));
- puts("fell!\n");
- } else {
- puts("Rose!\n");
- // TIM_CNT(TIM7) = 0;
- state.falling = true;
- exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_FALLING);
- }
+/*
+ * Free running ms timer.
+ */
+void setup_tim7(void)
+{
+ timer_reset(TIM7);
+ timer_set_prescaler(TIM7, 23999); // 24Mhz/1000hz - 1
+ timer_set_period(TIM7, 0xffff);
+ timer_enable_counter(TIM7);
}
-void setup_buttons(void) {
- /* Enable EXTI0 interrupt. */
- nvic_enable_irq(BUTTON_DISCO_USER_NVIC);
+void setup_buttons(void)
+{
+ /* Enable EXTI0 interrupt. */
+ nvic_enable_irq(BUTTON_DISCO_USER_NVIC);
- gpio_mode_setup(BUTTON_DISCO_USER_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, BUTTON_DISCO_USER_PIN);
+ gpio_mode_setup(BUTTON_DISCO_USER_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, BUTTON_DISCO_USER_PIN);
- /* Configure the EXTI subsystem. */
- exti_select_source(BUTTON_DISCO_USER_EXTI, BUTTON_DISCO_USER_PORT);
- state.falling = false;
- exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
- exti_enable_request(BUTTON_DISCO_USER_EXTI);
+ /* Configure the EXTI subsystem. */
+ exti_select_source(BUTTON_DISCO_USER_EXTI, BUTTON_DISCO_USER_PORT);
+ state.falling = false;
+ exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
+ exti_enable_request(BUTTON_DISCO_USER_EXTI);
}
-int main(void) {
- int i;
- int j = 0;
- clock_setup();
- gpio_setup();
- usart_setup();
- puts("hi guys!\n");
- setup_buttons();
- while (1) {
- puts("tick:");
- putchar('a' + (j++ % 26));
- gpio_toggle(GPIOB, GPIO7); /* LED on/off */
- for (i = 0; i < 100000; i++) /* Wait a bit. */
- __asm__("NOP");
- }
-
- return 0;
+int main(void)
+{
+ clock_setup();
+ gpio_setup();
+ usart_setup();
+ printf("hi guys!\n");
+ setup_buttons();
+ setup_tim6();
+ setup_tim7();
+ while (1) {
+ ;
+ }
+
+ return 0;
}
View
8 examples/stm32/l1/stm32l-discovery/button-irq-printf/syscfg.h
@@ -31,10 +31,10 @@ extern "C" {
#define BUTTON_DISCO_USER_isr exti0_isr
#define BUTTON_DISCO_USER_NVIC NVIC_EXTI0_IRQ
-
- struct state_t {
- bool falling;
- };
+ struct state_t {
+ bool falling;
+ int tickcount;
+ };
#ifdef __cplusplus

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