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--- stm32:peripherals:pwr_sleep [2016/10/13 11:10] – created feur
+++ stm32:peripherals:pwr_sleep [2019/09/16 07:19] (current) – [Programming Example] kjaz
@@ Line 1: / Line 1: @@
 ====== SLEEP Mode ======
+In SLEEP mode only the cpu clock is disabled, everything else stays as previously configured. \\ \\
+=== Enter SLEEP mode ===
+  * WFI (wait for interrupt) instuction enters SLEEP mode.
+\\
+=== Exit SLEEP mode ===
+  * Clear the EXTI (and, if not EXTI, the corresponding NVIC) pending bit.
+\\
+===== Programming Example =====
+The code snippet bellow shows how to enter (and exit) SLEEP mode.
+<code c>
+#include "reg_stm32f4xx.h"
+RCC->AHB1ENR |= (0x1 <<  0u);       /* Enable GPIOA clock */
+RCC->APB2ENR |= (0x1 << 14u);       /* Enable SYSCFG clock */
+/* Configure wake up pin (PA.0). */
+GPIOA->MODER &= ~(0x3 << 0u);         /* Clear existing mode bits 10 and 11. */
+GPIOA->PUPDR &= ~(0x3 << 0u);         /* Clear existing pull-up/-down bits 0 and 1. */
+GPIOA->PUPDR |= (0x1 << 0u);          /* Set pin 0 to pull-up mode. */
+/* Configure interrupt. */
+SYSCFG->EXTICR1 |= (0u << 0u);      /* Set EXTI0 to GPIOA. */
+EXTI->RTSR |= (0x1 << 0u);            /* Trigger on rising edge. */
+EXTI->IMR |= (0x1 << 0u);             /* Unmask interrupt line. */
+NVIC->ISER0 |= (0x1 << 6u);         /* Enable EXTI0 interrupt. */
+/* Disable SLEEPDEEP (STOP or STANDBY mode). */
+SCB->SCR &= ~(0x1 << 2u);
+/* -------------------- Enter SLEEP mode -------------------- */
+__asm volatile ("wfi");
+/* -------------------- Exit SLEEP mode --------------------- */
+/* Since all registers and the SRAM are untouched by the SLEEP mode,
+ * the program continues after the WFI instruction.
+ * No further steps required.
+ */
+</code>
+\\