From 3ebbd97760c816ab88fadf493e4dbe9b7e880965 Mon Sep 17 00:00:00 2001
From: Priec <filippriec@gmail.com>
Date: Wed, 3 Dec 2025 20:20:34 +0100
Subject: [PATCH] improvements to semestralka 2

---
 external_led_blinky/src/bin/main.rs |  4 ++--
 semestralka_2/src/bin/main.rs       |  6 ++++--
 semestralka_2/src/sleep/standby.rs  | 28 ++++++++++++++++++++++------
 semestralka_2/src/wakeup/iwdg.rs    |  2 ++
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/external_led_blinky/src/bin/main.rs b/external_led_blinky/src/bin/main.rs
index a04dc34..bb9f880 100644
--- a/external_led_blinky/src/bin/main.rs
+++ b/external_led_blinky/src/bin/main.rs
@@ -13,12 +13,12 @@ async fn main(_spawner: Spawner) {
     let p = init(Config::default());
 
     let mut output_pin = Output::new(p.PA3, Level::Low, Speed::Low);
-    let mut artificial_ground = Output::new(p.PB0, Level::Low, Speed::Low);
+    let mut _artificial_ground = Output::new(p.PB0, Level::Low, Speed::Low);
 
     loop {
         output_pin.set_high();
         Timer::after(Duration::from_millis(500)).await;
-        output_pin.set_low();
+        // output_pin.set_low();
         Timer::after(Duration::from_millis(500)).await;
     }
 }
diff --git a/semestralka_2/src/bin/main.rs b/semestralka_2/src/bin/main.rs
index 8d7ae4a..020cbf1 100644
--- a/semestralka_2/src/bin/main.rs
+++ b/semestralka_2/src/bin/main.rs
@@ -20,7 +20,7 @@ use dma_gpio::config::{
 use dma_gpio::hw_uart_pc::{driver::uart_task, usart1};
 use dma_gpio::wakeup::iwdg::{clear_wakeup_flags, init_watchdog};
 use dma_gpio::sleep::shutdown::enter_shutdown;
-use dma_gpio::sleep::standby::enter_standby_with_sram2_retention;
+use dma_gpio::sleep::standby;
 use {defmt_rtt as _, panic_probe as _};
 
 bind_interrupts!(struct Irqs {
@@ -70,7 +70,9 @@ async fn main(spawner: Spawner) {
 
     loop {
         info!("entering shutdown");
-        enter_standby_with_sram2_retention();
+        // enter_shutdown();
+        info!("shutdown");
+        standby::enter_standby_with_sram2_full();
         cortex_m::asm::wfi();
         yield_now().await;
     }
diff --git a/semestralka_2/src/sleep/standby.rs b/semestralka_2/src/sleep/standby.rs
index 3c4ad48..b07b1fe 100644
--- a/semestralka_2/src/sleep/standby.rs
+++ b/semestralka_2/src/sleep/standby.rs
@@ -12,12 +12,17 @@ pub fn enter_standby() -> ! {
     cortex_m::asm::udf(); // never happen marker
 }
 
-pub fn enter_standby_with_sram2_retention() -> ! {
-    sram2_retention();
+pub fn enter_standby_with_sram2_8kb() -> ! {
+    sram2_8kb_retention();
     enter_standby();
 }
 
-pub fn sram2_retention() {
+pub fn enter_standby_with_sram2_full() -> ! {
+    sram2_full_retention();
+    enter_standby();
+}
+
+pub fn sram2_full_retention() {
     unsafe extern "C" {
         fn HAL_PWREx_EnableSRAM2ContentStandbyRetention(sram2_pages: u32);
     }
@@ -25,18 +30,29 @@ pub fn sram2_retention() {
     unsafe {
         // 0x60 = PWR_SRAM2_FULL_STANDBY = PWR_CR1_RRSB1 | PWR_CR1_RRSB2
         // See: STM32U5xx HAL: stm32u5xx_hal_pwr_ex.h line 227
-        //      CMSIS: PWR_CR1_RRSB1=0x20, PWR_CR1_RRSB2=0x40
+        // PWR_CR1_RRSB1=0x20, PWR_CR1_RRSB2=0x40
         HAL_PWREx_EnableSRAM2ContentStandbyRetention(0x60);
     }
 }
 
-pub fn disable_sram2_retention() {
+pub fn sram2_8kb_retention() {
+    unsafe extern "C" {
+        fn HAL_PWREx_EnableSRAM2ContentStandbyRetention(sram2_pages: u32);
+    }
+
+    unsafe {
+        // 0x40 = PWR_SRAM2_PAGE1_STANDBY = PWR_CR1_RRSB2
+        // 8KB retention only
+        HAL_PWREx_EnableSRAM2ContentStandbyRetention(0x40);
+    }
+}
+
+pub fn disable_sram2_full_retention() {
     unsafe extern "C" {
         fn HAL_PWREx_DisableSRAM2ContentStandbyRetention(sram2_pages: u32);
     }
 
     unsafe {
-        // Disable full SRAM2 retention
         HAL_PWREx_DisableSRAM2ContentStandbyRetention(0x60);
     }
 }
diff --git a/semestralka_2/src/wakeup/iwdg.rs b/semestralka_2/src/wakeup/iwdg.rs
index b9ccb33..bffdc3c 100644
--- a/semestralka_2/src/wakeup/iwdg.rs
+++ b/semestralka_2/src/wakeup/iwdg.rs
@@ -6,6 +6,7 @@ use embassy_stm32::wdg::IndependentWatchdog;
 use embassy_stm32::Peri;
 use embassy_time::{Duration, Timer};
 use embassy_stm32::pac;
+use crate::sleep::standby;
 
 use crate::config::WATCHDOG_TIMEOUT_US;
 
@@ -20,6 +21,7 @@ use crate::config::WATCHDOG_TIMEOUT_US;
 /// - `PWR_SR` — Power Control / Status
 pub fn clear_wakeup_flags() {
     info!("Clearing wakeup flags...");
+    standby::disable_sram2_full_retention();
 
     // Clear reset flags
     // let rcc = unsafe { &*pac::RCC::ptr() };