working uart but not waking after sleep

semestralka_2_uart/src/sleep/standby.rs

@@ -0,0 +1,58 @@
+// src/sleep/standby.rs
+
+pub fn enter_standby() -> ! {
+    unsafe extern "C" {
+        fn HAL_PWR_EnterSTANDBYMode();
+    }
+    
+    unsafe {
+        HAL_PWR_EnterSTANDBYMode();
+    }
+    
+    cortex_m::asm::udf(); // never happen marker
+}
+
+pub fn enter_standby_with_sram2_8kb() -> ! {
+    sram2_8kb_retention();
+    enter_standby();
+}
+
+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);
+    }
+
+    unsafe {
+        // 0x60 = PWR_SRAM2_FULL_STANDBY = PWR_CR1_RRSB1 | PWR_CR1_RRSB2
+        // See: STM32U5xx HAL: stm32u5xx_hal_pwr_ex.h line 227
+        // PWR_CR1_RRSB1=0x20, PWR_CR1_RRSB2=0x40
+        HAL_PWREx_EnableSRAM2ContentStandbyRetention(0x60);
+    }
+}
+
+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 {
+        HAL_PWREx_DisableSRAM2ContentStandbyRetention(0x60);
+    }
+}