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Update example to use timers as well.
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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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@karlp
karlp committed Nov 18, 2012
1 parent 20c2a14 commit b2fb224
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29 changes: 29 additions & 0 deletions examples/stm32/l1/stm32l-discovery/button-irq-printf/README
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@@ -1,3 +1,32 @@
* Prints to the screen when the button is pushed/released (irq driven) * Prints to the screen when the button is pushed/released (irq driven)
115200@8n1 console on PA2 (tx only) 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!



205 changes: 130 additions & 75 deletions examples/stm32/l1/stm32l-discovery/button-irq-printf/main.c
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Expand Up @@ -9,41 +9,53 @@
#include <libopencm3/stm32/l1/rcc.h> #include <libopencm3/stm32/l1/rcc.h>
#include <libopencm3/stm32/l1/gpio.h> #include <libopencm3/stm32/l1/gpio.h>
#include <libopencm3/stm32/exti.h> #include <libopencm3/stm32/exti.h>
#include <libopencm3/stm32/timer.h>
#include <libopencm3/stm32/usart.h> #include <libopencm3/stm32/usart.h>


#include "syscfg.h" #include "syscfg.h"


static struct state_t state; static struct state_t state;


void clock_setup(void) { void clock_setup(void)
/* Lots of things on all ports... */ {
rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOAEN); rcc_clock_setup_pll(&clock_vrange1_config[CLOCK_VRANGE1_HSI_PLL_24MHZ]);
rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOBEN); /* 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) { void gpio_setup(void)
gpio_mode_setup(LED_DISCO_GREEN_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_DISCO_GREEN_PIN); {
/* 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. */ /* Setup GPIO pins for USART2 transmit. */
gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2); gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);


/* Setup USART2 TX pin as alternate function. */ /* Setup USART2 TX pin as alternate function. */
gpio_set_af(GPIOA, GPIO_AF7, GPIO2); gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
} }


void usart_setup(void) { void usart_setup(void)
usart_set_baudrate(USART_CONSOLE, 115200); {
usart_set_databits(USART_CONSOLE, 8); usart_set_baudrate(USART_CONSOLE, 115200);
usart_set_stopbits(USART_CONSOLE, USART_STOPBITS_1); usart_set_databits(USART_CONSOLE, 8);
usart_set_mode(USART_CONSOLE, USART_MODE_TX); usart_set_stopbits(USART_CONSOLE, USART_STOPBITS_1);
usart_set_parity(USART_CONSOLE, USART_PARITY_NONE); usart_set_mode(USART_CONSOLE, USART_MODE_TX);
usart_set_flow_control(USART_CONSOLE, USART_FLOWCONTROL_NONE); 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); /* Finally enable the USART. */
usart_enable(USART_CONSOLE);
} }


/** /**
Expand All @@ -53,65 +65,108 @@ void usart_setup(void) {
* @param len * @param len
* @return * @return
*/ */
int _write(int file, char *ptr, int len) { int _write(int file, char *ptr, int len)
int i; {

int i;
if (file == STDOUT_FILENO || file == STDERR_FILENO) {
for (i = 0; i < len; i++) { if (file == STDOUT_FILENO || file == STDERR_FILENO) {
if (ptr[i] == '\n') { for (i = 0; i < len; i++) {
usart_send_blocking(USART_CONSOLE, '\r'); if (ptr[i] == '\n') {
} usart_send_blocking(USART_CONSOLE, '\r');
usart_send_blocking(USART_CONSOLE, ptr[i]); }
} usart_send_blocking(USART_CONSOLE, ptr[i]);
return i; }
} return i;
errno = EIO; }
return -1; 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); * Free running ms timer.
if (state.falling) { */
state.falling = false; void setup_tim7(void)
exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING); {
// ILOG("fell: %d\n", TIM_CNT(TIM7)); timer_reset(TIM7);
puts("fell!\n"); timer_set_prescaler(TIM7, 23999); // 24Mhz/1000hz - 1
} else { timer_set_period(TIM7, 0xffff);
puts("Rose!\n"); timer_enable_counter(TIM7);
// TIM_CNT(TIM7) = 0;
state.falling = true;
exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_FALLING);
}
} }


void setup_buttons(void) { void setup_buttons(void)
/* Enable EXTI0 interrupt. */ {
nvic_enable_irq(BUTTON_DISCO_USER_NVIC); /* 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. */ /* Configure the EXTI subsystem. */
exti_select_source(BUTTON_DISCO_USER_EXTI, BUTTON_DISCO_USER_PORT); exti_select_source(BUTTON_DISCO_USER_EXTI, BUTTON_DISCO_USER_PORT);
state.falling = false; state.falling = false;
exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING); exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
exti_enable_request(BUTTON_DISCO_USER_EXTI); exti_enable_request(BUTTON_DISCO_USER_EXTI);
} }


int main(void) { int main(void)
int i; {
int j = 0; clock_setup();
clock_setup(); gpio_setup();
gpio_setup(); usart_setup();
usart_setup(); printf("hi guys!\n");
puts("hi guys!\n"); setup_buttons();
setup_buttons(); setup_tim6();
while (1) { setup_tim7();
puts("tick:"); while (1) {
putchar('a' + (j++ % 26)); ;
gpio_toggle(GPIOB, GPIO7); /* LED on/off */ }
for (i = 0; i < 100000; i++) /* Wait a bit. */
__asm__("NOP"); return 0;
}

return 0;
} }
8 changes: 4 additions & 4 deletions examples/stm32/l1/stm32l-discovery/button-irq-printf/syscfg.h
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Expand Up @@ -31,10 +31,10 @@ extern "C" {
#define BUTTON_DISCO_USER_isr exti0_isr #define BUTTON_DISCO_USER_isr exti0_isr
#define BUTTON_DISCO_USER_NVIC NVIC_EXTI0_IRQ #define BUTTON_DISCO_USER_NVIC NVIC_EXTI0_IRQ



struct state_t {
struct state_t { bool falling;
bool falling; int tickcount;
}; };




#ifdef __cplusplus #ifdef __cplusplus
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