examples/lorawan: move enabling of sleep modes to C code

examples/lorawan/Makefile

@@ -53,10 +53,6 @@ else ifeq (abp,$(ACTIVATION_MODE))
   CFLAGS += -DUSE_ABP
 endif
 
-# Enable deep sleep power mode (e.g. STOP mode on STM32) which
-# in general provides RAM retention after wake-up.
-CFLAGS += -DPM_BLOCKER_INITIAL=0x00000001
-
 # Comment this out to disable code in RIOT that does safety checking
 # which is not needed in a production environment but helps in the
 # development process:

examples/lorawan/main.c

@@ -27,6 +27,7 @@
 #include "thread.h"
 #include "fmt.h"
 
+#include "periph/pm.h"
 #if IS_USED(MODULE_PERIPH_RTC)
 #include "periph/rtc.h"
 #else
@@ -148,6 +149,16 @@ int main(void)
     puts("LoRaWAN Class A low-power application");
     puts("=====================================");
 
+    /*
+     * Enable deep sleep power mode (e.g. STOP mode on STM32) which
+     * in general provides RAM retention after wake-up.
+     */
+#if IS_USED(MODULE_PM_LAYERED)
+    for (unsigned i = 1; i < PM_NUM_MODES; ++i) {
+        pm_unblock(i);
+    }
+#endif
+
     /* Initialize the radio driver */
 #if IS_USED(MODULE_SX127X)
     sx127x_setup(&sx127x, &sx127x_params[0], 0);