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stm32: morse timer: standardize example

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Simplify, clarify and synchronize the two morse LED blinker examples.
Prepare for one day extracting the core as common morse example code.
This commit is contained in:
Karl Palsson
2016-12-17 00:21:19 +00:00
parent d2abd471a5
commit 9af2b8c7fb
4 changed files with 143 additions and 120 deletions
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6
examples/stm32/f4/stm32f4-discovery/timer/README.md
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@@ -1,14 +1,14 @@
# README
This example demonstrates the use of timers to trigger an interrupt. This
example will toggle two LEDs spelling out the following morse code:
example will toggle a LED spelling out the following morse code:
SOS -> ...---...
Where dots are .1s, dashes .2s, gaps .05s and the word pause .5s.
using international morse timing, with a dot element of 100ms
It's intended for the ST STM32F4DISCOVERY eval board. It should blink
the LEDs on the board.
a LED on the board.
## Board connections

100
examples/stm32/f4/stm32f4-discovery/timer/timer.c
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@@ -22,41 +22,45 @@
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/timer.h>
#include <libopencm3/stm32/exti.h>
#include <libopencmsis/core_cm3.h>
#ifndef ARRAY_LEN
#define ARRAY_LEN(array) (sizeof((array))/sizeof((array)[0]))
#endif
uint16_t frequency_sequence[18] = {
1000,
500,
1000,
500,
1000,
500,
2000,
500,
2000,
500,
2000,
500,
1000,
500,
1000,
500,
1000,
5000,
#define LED1_PORT GPIOD
#define LED1_PIN GPIO12
/* Morse standard timings */
#define ELEMENT_TIME 500
#define DIT (1*ELEMENT_TIME)
#define DAH (3*ELEMENT_TIME)
#define INTRA (1*ELEMENT_TIME)
#define INTER (3*ELEMENT_TIME)
#define WORD (7*ELEMENT_TIME)
uint16_t frequency_sequence[] = {
DIT,
INTRA,
DIT,
INTRA,
DIT,
INTER,
DAH,
INTRA,
DAH,
INTRA,
DAH,
INTER,
DIT,
INTRA,
DIT,
INTRA,
DIT,
WORD,
};
uint16_t frequency_sel = 0;
uint16_t compare_time;
uint16_t new_time;
uint16_t frequency;
int debug = 0;
int frequency_sel = 0;
static void clock_setup(void)
{
@@ -68,12 +72,9 @@ static void gpio_setup(void)
/* Enable GPIO clock for leds. */
rcc_periph_clock_enable(RCC_GPIOD);
/* Set GPIO12 (in GPIO port D) to 'output push-pull'. */
gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT,
GPIO_PUPD_NONE, GPIO12 | GPIO13);
gpio_set(GPIOD, GPIO12);
gpio_clear(GPIOD, GPIO13);
/* Enable led as output */
gpio_mode_setup(LED1_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED1_PIN);
gpio_set(LED1_PORT, LED1_PIN);
}
static void tim_setup(void)
@@ -95,15 +96,16 @@ static void tim_setup(void)
* is strictly unnecessary, but demos the api for alternative settings)
*/
timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT,
TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
/*
* Please take note that the clock source for STM32F4 timers
* might not be the raw APB1/APB2 clocks. In various conditions they
* are doubled. See the Reference Manual for full details!
* In our case, TIM2 on APB1 is running at double frequency, so this
* sets the prescaler to have the timer run at 10kHz
*/
timer_set_prescaler(TIM2, ((rcc_apb1_frequency * 2) / 10000));
TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
/*
* Please take note that the clock source for STM32 timers
* might not be the raw APB1/APB2 clocks. In various conditions they
* are doubled. See the Reference Manual for full details!
* In our case, TIM2 on APB1 is running at double frequency, so this
* sets the prescaler to have the timer run at 5kHz
*/
timer_set_prescaler(TIM2, ((rcc_apb1_frequency * 2) / 5000));
/* Disable preload. */
timer_disable_preload(TIM2);
@@ -113,7 +115,7 @@ static void tim_setup(void)
timer_set_period(TIM2, 65535);
/* Set the initual output compare value for OC1. */
timer_set_oc_value(TIM2, TIM_OC1, 1000);
timer_set_oc_value(TIM2, TIM_OC1, frequency_sequence[frequency_sel++]);
/* Counter enable. */
timer_enable_counter(TIM2);
@@ -133,11 +135,11 @@ void tim2_isr(void)
* Get current timer value to calculate next
* compare register value.
*/
compare_time = timer_get_counter(TIM2);
uint16_t compare_time = timer_get_counter(TIM2);
/* Calculate and set the next compare value. */
frequency = frequency_sequence[frequency_sel++];
new_time = compare_time + frequency;
uint16_t frequency = frequency_sequence[frequency_sel++];
uint16_t new_time = compare_time + frequency;
timer_set_oc_value(TIM2, TIM_OC1, new_time);
if (frequency_sel == ARRAY_LEN(frequency_sequence)) {
@@ -145,8 +147,7 @@ void tim2_isr(void)
}
/* Toggle LED to indicate compare event. */
gpio_toggle(GPIOD, GPIO12);
gpio_toggle(GPIOD, GPIO13);
gpio_toggle(LED1_PORT, LED1_PIN);
}
}
@@ -164,8 +165,9 @@ int main(void)
* an interrupt masked by PRIMASK becomes pending
* a Debug Entry request
*/
while (1)
while (1) {
__WFI(); /* Wait For Interrupt. */
}
return 0;
}