only: wait until board has turned itself on

firmware/hw_layer/mmc_card.cpp

@@ -35,6 +35,7 @@ static int totalSyncCounter = 0;
 #include "mmc_card.h"
 #include "ff.h"
 #include "mass_storage_init.h"
+#include "hellen_meta.h"
 
 #include "rtc_helper.h"
 
@@ -527,6 +528,15 @@ static THD_FUNCTION(MMCmonThread, arg) {
 	(void)arg;
 	chRegSetThreadName("MMC Card Logger");
 
+#if HW_HELLEN && EFI_PROD_CODE
+  // on mega-module we manage SD card power supply
+  while (!getHellenBoardEnabled()) {
+    // wait until board enables peripheral
+    chThdSleepMilliseconds(100);
+  }
+  chThdSleepMilliseconds(300);
+#endif
+
 	if (!mountMmc()) {
 		// no card present (or mounted via USB), don't do internal logging
 		return;