EMTime/libopencm3-examples
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

stm32l4: basic uart/exti/led/clock demo

Browse Source 
No miniblink, let people interpret a more useful example.
This commit is contained in:
Karl Palsson
2018-03-03 23:50:46 +00:00
parent 7d6a2e36ee
commit b8b9720926
3 changed files with 228 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
examples/stm32/l4/stm32l476g-disco/basics/Makefile Normal file
View File

@@ -0,0 +1,21 @@
##
## This file is part of the libopencm3 project.
##
## This library is free software: you can redistribute it and/or modify
## it under the terms of the GNU Lesser General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## This library is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with this library. If not, see <http://www.gnu.org/licenses/>.
##
BINARY=basics
DEVICE=stm32l476vg
include ../../Makefile.include

8
examples/stm32/l4/stm32l476g-disco/basics/README.md Normal file
View File

@@ -0,0 +1,8 @@
This demonstrates some basics on the L476G disco board.
* printf via usart2 to the attached stlink virtual com port. 115200@8n1
* pll configuration from hsi
* flash wait state configuration
* basic led blinking
* exti interrupts for buttons
* simple timer usage.

199
examples/stm32/l4/stm32l476g-disco/basics/basics.c Normal file
View File

@@ -0,0 +1,199 @@
/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2018 Karl Palsson <karlp@tweak.net.au>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/stm32/exti.h>
#include <libopencm3/stm32/flash.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/timer.h>
#include <libopencm3/stm32/usart.h>
#define LED_GREEN_PORT GPIOE
#define LED_GREEN_PIN GPIO8
#define LED_RED_PORT GPIOB
#define LED_RED_PIN GPIO2
/* joysticks are on PA0,1,2,3,5 (center, left, right, up, down) */
#define JOY_PORT GPIOA
#define JOYC_EXTI EXTI0
#define JOYC_PIN GPIO0
#define JOYC_NVIC NVIC_EXTI0_IRQ
#define USART_CONSOLE USART2 /* PD5/6 , af7 */
int _write(int file, char *ptr, int len);
struct state_t {
bool falling;
int last_hold;
//int tickcount;
};
static struct state_t state;
static void clock_setup(void)
{
/* FIXME - this should eventually become a clock struct helper setup */
rcc_osc_on(RCC_HSI16);
flash_prefetch_enable();
flash_set_ws(4);
flash_dcache_enable();
flash_icache_enable();
/* 16MHz / 4 = > 4 * 40 = 160MHz VCO => 80MHz main pll */
rcc_set_main_pll(RCC_PLLCFGR_PLLSRC_HSI16, 4, 40,
0, 0, RCC_PLLCFGR_PLLR_DIV2);
rcc_osc_on(RCC_PLL);
/* either rcc_wait_for_osc_ready() or do other things */
/* Enable clocks for the ports we need */
rcc_periph_clock_enable(RCC_GPIOA);
rcc_periph_clock_enable(RCC_GPIOB);
rcc_periph_clock_enable(RCC_GPIOD);
rcc_periph_clock_enable(RCC_GPIOE);
/* Enable clocks for peripherals we need */
rcc_periph_clock_enable(RCC_USART2);
rcc_periph_clock_enable(RCC_TIM7);
rcc_periph_clock_enable(RCC_SYSCFG);
rcc_set_sysclk_source(RCC_CFGR_SW_PLL); /* careful with the param here! */
rcc_wait_for_sysclk_status(RCC_PLL);
/* FIXME - eventually handled internally */
rcc_ahb_frequency = 80e6;
rcc_apb1_frequency = 80e6;
rcc_apb2_frequency = 80e6;
}
static void usart_setup(void)
{
/* Setup GPIO pins for USART2 transmit. */
gpio_mode_setup(GPIOD, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO5|GPIO6);
/* Setup USART2 TX pin as alternate function. */
gpio_set_af(GPIOD, GPIO_AF7, GPIO5);
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);
}
/**
* Use USART_CONSOLE as a console.
* This is a syscall for newlib
* @param file
* @param ptr
* @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;
}
void exti0_isr(void)
{
exti_reset_request(JOYC_EXTI);
if (state.falling) {
gpio_clear(LED_RED_PORT, LED_RED_PIN);
state.falling = false;
state.last_hold = TIM_CNT(TIM7);
exti_set_trigger(JOYC_EXTI, EXTI_TRIGGER_RISING);
} else {
/* pushed */
gpio_set(LED_RED_PORT, LED_RED_PIN);
state.falling = true;
TIM_CNT(TIM7) = 0;
state.last_hold = 0;
exti_set_trigger(JOYC_EXTI, EXTI_TRIGGER_FALLING);
}
}
/*
* Free running ms timer.
*/
static void setup_tim7(void)
{
rcc_periph_reset_pulse(RST_TIM7);
timer_set_prescaler(TIM7, rcc_apb1_frequency / 1e3 - 1);
timer_set_period(TIM7, 0xffff);
timer_enable_counter(TIM7);
}
int main(void)
{
int j = 0;
clock_setup();
usart_setup();
printf("hi guys!\n");
/* green led for ticking */
gpio_mode_setup(LED_GREEN_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE,
LED_GREEN_PIN);
/* red led for buttons */
gpio_mode_setup(LED_RED_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE,
LED_RED_PIN);
setup_tim7();
gpio_mode_setup(JOY_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, JOYC_PIN);
nvic_enable_irq(JOYC_NVIC);
exti_select_source(JOYC_EXTI, JOY_PORT);
state.falling = false;
exti_set_trigger(JOYC_EXTI, EXTI_TRIGGER_RISING);
exti_enable_request(JOYC_EXTI);
while (1) {
printf("tick: %d\n", j++);
if (state.last_hold) {
printf("button was held for %d ms\n", state.last_hold);
state.last_hold = 0;
}
gpio_toggle(LED_GREEN_PORT, LED_GREEN_PIN);
for (int i = 0; i < 4000000; i++) { /* Wait a bit. */
__asm__("NOP");
}
}
return 0;
}