add examples to STM32L100C-DISCO board

examples/stm32/l1/stm32l1-discovery/button-irq-printf-lowpower/Makefile

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+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <[email protected]>
+##
+## 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 = main
+
+LDSCRIPT = $(OPENCM3_DIR)/lib/stm32/l1/stm32l100xc.ld
+
+include ../../Makefile.include
+

examples/stm32/l1/stm32l1-discovery/button-irq-printf-lowpower/README.md

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+# README
+
+In order for this example to work with STM32L100C-DISCO,
+the external 32.768kHz crystal X3 together with the surrounding components (R24, R25, C15, C16) should be installed.
+
+This is _functionally_ identical to the "button-irq-printf"
+example, but has been modified to use some low power features.
+
+There is a 115200@8n1 console on PA2, which prints a tick count every second,
+and when the user push button is pressed, the time it is held down for is
+timed (in milliseconds)
+
+Instead of free running timers and busy loops, this version uses the RTC
+module and attempts to sleep as much as possible, including while the button
+is pressed.
+
+## Status
+Only very basic power savings are done!
+
+Current consumption, led off/on, 16Mhz HSI:    2.7mA/5.4mA
+Current consumption, led off/on,  4Mhz HSI:    1.4mA/?.?mA
+Current consumption, led off/on,  4Mhz MSI:    0.9mA/?.?mA

examples/stm32/l1/stm32l1-discovery/button-irq-printf-lowpower/main.c

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <[email protected]>
+ *
+ * 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/cm3/scb.h>
+#include <libopencm3/stm32/dbgmcu.h>
+#include <libopencm3/stm32/exti.h>
+#include <libopencm3/stm32/flash.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/pwr.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/rtc.h>
+#include <libopencm3/stm32/timer.h>
+#include <libopencm3/stm32/usart.h>
+
+#include "syscfg.h"
+
+//#define FULL_USER_EXPERIENCE
+
+static volatile struct state_t state;
+
+int _write(int file, char *ptr, int len);
+
+static inline __attribute__((always_inline)) void __WFI(void)
+{
+	__asm volatile ("wfi");
+}
+
+static 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 USART2 TX pin as alternate function. */
+	gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+}
+
+void BUTTON_DISCO_USER_isr(void)
+{
+	exti_reset_request(BUTTON_DISCO_USER_EXTI);
+	state.pressed = true;
+	if (state.falling) {
+		state.falling = false;
+		exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_RISING);
+		state.hold_time = TIM_CNT(TIMER_BUTTON_PRESS);
+	} else {
+		state.falling = true;
+		exti_set_trigger(BUTTON_DISCO_USER_EXTI, EXTI_TRIGGER_FALLING);
+		state.hold_time = TIM_CNT(TIMER_BUTTON_PRESS) = 0;
+	}
+}
+
+static 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);
+
+	/* 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);
+}
+
+static 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);
+}
+
+/**
+ * Use USART_CONSOLE as a console.
+ * @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;
+}
+
+/*
+ * Free running ms timer.
+ */
+static void setup_button_press_timer(void)
+{
+	rcc_periph_reset_pulse(TIMER_BUTTON_PRESS_RST);
+	timer_set_prescaler(TIMER_BUTTON_PRESS, 3999); /* 4Mhz/1000hz - 1 */
+	timer_set_period(TIMER_BUTTON_PRESS, 0xffff);
+	timer_enable_counter(TIMER_BUTTON_PRESS);
+}
+
+static int setup_rtc(void)
+{
+	/* turn on power block to enable unlocking */
+	rcc_periph_clock_enable(RCC_PWR);
+	pwr_disable_backup_domain_write_protect();
+
+	/* reset rtc */
+	RCC_CSR |= RCC_CSR_RTCRST;
+	RCC_CSR &= ~RCC_CSR_RTCRST;
+
+	/* We want to use the LSE fitted on the discovery board */
+	rcc_osc_on(RCC_LSE);
+	rcc_wait_for_osc_ready(RCC_LSE);
+
+	/* Select the LSE as rtc clock */
+	rcc_rtc_select_clock(RCC_CSR_RTCSEL_LSE);
+
+	/* ?! Stdperiph examples don't turn this on until _afterwards_ which
+	 * simply doesn't work.  It must be on at least to be able to
+	 * configure it */
+	RCC_CSR |= RCC_CSR_RTCEN;
+
+	rtc_unlock();
+
+	/* enter init mode */
+	RTC_ISR |= RTC_ISR_INIT;
+	while ((RTC_ISR & RTC_ISR_INITF) == 0);
+
+	/* set synch prescaler, using defaults for 1Hz out */
+	uint32_t sync = 255;
+	uint32_t async = 127;
+	rtc_set_prescaler(sync, async);
+
+	/* load time and date here if desired, and hour format */
+
+	/* exit init mode */
+	RTC_ISR &= ~(RTC_ISR_INIT);
+
+	/* and write protect again */
+	rtc_lock();
+
+	/* and finally enable the clock */
+	RCC_CSR |= RCC_CSR_RTCEN;
+
+	/* And wait for synchro.. */
+	rtc_wait_for_synchro();
+	return 0;
+}
+
+static int setup_rtc_wakeup(int period)
+{
+	rtc_unlock();
+
+	/* ensure wakeup timer is off */
+	RTC_CR &= ~RTC_CR_WUTE;
+
+	/* Wait until we can write */
+	while ((RTC_ISR & RTC_ISR_WUTWF) == 0);
+
+	RTC_WUTR = period - 1;
+
+	/* Use the 1Hz clock as source */
+	RTC_CR &= ~(RTC_CR_WUCLKSEL_MASK << RTC_CR_WUCLKSEL_SHIFT);
+	RTC_CR |= (RTC_CR_WUCLKSEL_SPRE << RTC_CR_WUCLKSEL_SHIFT);
+
+	/* Restart WakeUp unit */
+	RTC_CR |= RTC_CR_WUTE;
+
+	/* interrupt configuration */
+
+	/* also, let's have an interrupt */
+	RTC_CR |= RTC_CR_WUTIE;
+
+	/* done with rtc registers, lock them again */
+	rtc_lock();
+
+	nvic_enable_irq(NVIC_RTC_WKUP_IRQ);
+
+	/* EXTI configuration */
+	/* Configure the EXTI subsystem. */
+	/* not needed, this chooses ports
+	   exti_select_source(EXTI20, BUTTON_DISCO_USER_PORT);
+	*/
+	exti_set_trigger(EXTI20, EXTI_TRIGGER_RISING);
+	exti_enable_request(EXTI20);
+	return 0;
+}
+
+void rtc_wkup_isr(void)
+{
+	/* clear flag, not write protected */
+	RTC_ISR &= ~(RTC_ISR_WUTF);
+	exti_reset_request(EXTI20);
+	state.rtc_ticked = true;
+}
+
+static int process_state(volatile struct state_t *st)
+{
+	if (st->rtc_ticked) {
+		st->rtc_ticked = 0;
+		printf("Tick: %x\n", (unsigned int) RTC_TR);
+#if defined(FULL_USER_EXPERIENCE)
+		gpio_toggle(LED_DISCO_GREEN_PORT, LED_DISCO_GREEN_PIN);
+#else
+		gpio_clear(LED_DISCO_GREEN_PORT, LED_DISCO_GREEN_PIN);
+#endif
+	}
+	if (st->pressed) {
+		st->pressed = false;
+		if (st->falling) {
+			gpio_set(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
+			printf("Pushed down!\n");
+		} else {
+			gpio_clear(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
+			printf("held: %u ms\n", st->hold_time);
+		}
+	}
+	return 0;
+}
+
+static void reset_clocks(void)
+{
+	/* 4MHz MSI raw range 2*/
+	struct rcc_clock_scale myclock_config = {
+		.hpre = RCC_CFGR_HPRE_SYSCLK_NODIV,
+		.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
+		.ppre2 = RCC_CFGR_PPRE2_HCLK_NODIV,
+		.voltage_scale = PWR_SCALE2,
+		.flash_config = FLASH_ACR_LATENCY_0WS,
+		.apb1_frequency = 4194000,
+		.apb2_frequency = 4194000,
+		.msi_range = RCC_ICSCR_MSIRANGE_4MHZ,
+	};
+	rcc_clock_setup_msi(&myclock_config);
+
+	/* buttons and uarts */
+	rcc_periph_clock_enable(RCC_GPIOA);
+	/* user feedback leds */
+	rcc_periph_clock_enable(RCC_GPIOC);
+	/* Enable clocks for USART2. */
+	rcc_periph_clock_enable(RCC_USART2);
+	/* And a timers for button presses */
+	rcc_periph_clock_enable(RCC_TIM7);
+}
+
+int main(void)
+{
+	reset_clocks();
+	gpio_setup();
+	usart_setup();
+	setup_buttons();
+	setup_button_press_timer();
+	printf("we're awake!\n");
+
+	setup_rtc();
+	setup_rtc_wakeup(1);
+
+	while (1) {
+		PWR_CR |= PWR_CR_LPSDSR;
+		pwr_set_stop_mode();
+		__WFI();
+		reset_clocks();
+		process_state(&state);
+	}
+
+	return 0;
+}