Use tickless idle to save power.

config/lwipopts.h

@@ -90,6 +90,7 @@ int sys_random(void);
 #define WDCFG_FIRMWARE "43362A2.bin"
 #define WDCFG_FIRMWARE_PATH "/firmware", "/flash"
 
+//#define TIMERS_DEBUG LWIP_DBG_ON
 //#define TCPIP_DEBUG      LWIP_DBG_ON
 //#define NETIF_DEBUG      LWIP_DBG_ON
 //#define SOCKETS_DEBUG    LWIP_DBG_OFF

config/pos_cmsis.h

@@ -33,6 +33,7 @@
 void USART2_IRQHandler(void);
 void SDIO_irq(void);
 void DMA2_Stream3_irq(void);
+void RTC_WKUP_IRQHandler(void);
 
 /*
  * These are interrupt handlers inside Wiced usart code.

config/poscfg.h

@@ -536,13 +536,18 @@
 
 #define PORTCFG_IRQ_STACK_SIZE 2048
 #define PORTCFG_VECTORS 1
-#define PORTCFG_TICK_SYSTICK 1
 #define PORTCFG_CONOUT_ITM 0
 #define PORTCFG_API_MAX_PRI 2 // same as used by Wiced
 /*
  * WIfiMCU has console at usart 2.
  */
 #define PORTCFG_CON_USART 2
 
+#define PORTCFG_TICK_SYSTICK 0
+#define PORTCFG_TICK_RTC 1
+#define PORTCFG_POWER_TICKLESS_MIN MS(20)
+#define POSCFG_FEATURE_POWER 1
+#define POSCFG_FEATURE_POWER_WAKEUP 1
+#define POSCFG_FEATURE_TICKLESS 1
 
 #endif /* _POSCFG_H */

config/stm32f4xx_conf.h

@@ -42,6 +42,8 @@
 #include "stm32f4xx_spi.h"
 #include "stm32f4xx_wwdg.h"
 #include "stm32f4xx_rtc.h"
+#include "stm32f4xx_exti.h"
+#include "stm32f4xx_pwr.h"
 #include "stm32f4xx_flash.h"
 #include "misc.h"
 

main.c

@@ -40,6 +40,7 @@
 #include "lwip/mem.h"
 #include "lwip/memp.h"
 #include "lwip/sys.h"
+#include "lwip/netifapi.h"
 
 #include "lwip/stats.h"
 #include "lwip/inet.h"
@@ -154,7 +155,16 @@ static void mainTask(void* arg)
 
   eshStartTelnetd();
   guiStart();
+
+/*
+ * Enable sleep. It is initially enabled in pico]OS, but Wiced
+ * disables it during initialization.
+ */
+  posPowerEnableSleep();
+
+#if NOSCFG_FEATURE_CONIN
   eshConsole();
+#endif
 }
 
 
@@ -185,6 +195,17 @@ int main(int argc, char **argv)
 
 #endif
 
+#if !NOSCFG_FEATURE_CONIN
+
+/* 
+ * STM32 cannot sleep deep if USART input is needed (because it needs clock).
+ */
+  PWR->CR  |= PWR_CR_LPDS;
+  PWR->CR  &= (unsigned long) ( ~( PWR_CR_PDDS ) );
+
+  SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
+#endif
+
   nosInit(mainTask, NULL, 1, 5000, 512);
   return 0;
 }

sta.c

@@ -109,11 +109,8 @@ void ifStatusCallback(struct netif *netif)
     /*
      * Powersave experiments. Without these, about 73 mA is used.
      * With wifi powersave, 15-20 mA is used.
-     * Platform powersave cannot be used (yet), as it will stop
-     * systick.
      */
     //wwd_wifi_enable_powersave();
-    //platform_mcu_powersave_enable();
 
     potatoStart();
   }

startup.c

@@ -47,10 +47,11 @@ void Default_Handler()
 
 extern unsigned int __stack[];
 
+PORT_WEAK_HANDLER(SysTick_Handler);
 PORT_WEAK_HANDLER(WWDG_irq);
 PORT_WEAK_HANDLER(PVD_irq);
 PORT_WEAK_HANDLER(TAMP_STAMP_irq);
-PORT_WEAK_HANDLER(RTC_WKUP_irq);
+PORT_WEAK_HANDLER(RTC_WKUP_IRQHandler);
 PORT_WEAK_HANDLER(FLASH_irq);
 PORT_WEAK_HANDLER(RCC_irq);
 PORT_WEAK_HANDLER(EXTI0_irq);
@@ -151,7 +152,7 @@ PortExcHandlerFunc vectorTable[] __attribute__ ((section(".vectors"))) =
     WWDG_irq,                   // Window WatchDog
     PVD_irq,                    // PVD through EXTI Line detection
     TAMP_STAMP_irq,             // Tamper and TimeStamps through the EXTI line
-    RTC_WKUP_irq,               // RTC Wakeup through the EXTI line
+    RTC_WKUP_IRQHandler,        // RTC Wakeup through the EXTI line
     FLASH_irq,                  // FLASH
     RCC_irq,                    // RCC
     EXTI0_irq,                  // EXTI Line0