diff --git a/firmware/CHANGELOG.md b/firmware/CHANGELOG.md
index 24ba2bd8a2..88dc04acaf 100644
--- a/firmware/CHANGELOG.md
+++ b/firmware/CHANGELOG.md
@@ -28,6 +28,7 @@ All notable user-facing or behavior-altering changes will be documented in this
 ## XXX 2021 Release
 
 ### Added
+ - USB Mass Storage: The connected SD card will be mounted over USB if rusEFI connected to a PC via USB.
  - GM 60/2/2/2 trigger https://github.com/rusefi/rusefi/wiki/All-Supported-Triggers#gm
  - TriTach trigger https://github.com/rusefi/rusefi/wiki/All-Supported-Triggers#tritach
  - Skoda Favorit trigger https://github.com/rusefi/rusefi/wiki/All-Supported-Triggers#skoda-favorit
diff --git a/firmware/config/boards/microrusefi/board.mk b/firmware/config/boards/microrusefi/board.mk
index 445d6123ee..d0a5d7792c 100644
--- a/firmware/config/boards/microrusefi/board.mk
+++ b/firmware/config/boards/microrusefi/board.mk
@@ -30,6 +30,9 @@ EFI_CONSOLE_TTL_PINS = -DEFI_CONSOLE_TX_BRAIN_PIN=GPIOB_10 -DEFI_CONSOLE_RX_BRAI
 # Add them all together
 DDEFS += -DEFI_USE_OSC=TRUE -DFIRMWARE_ID=\"microRusEFI\" $(DEFAULT_ENGINE_TYPE) $(LED_CRITICAL_ERROR_BRAIN_PIN) $(EFI_CONSOLE_TTL_PINS) -DEFI_SOFTWARE_KNOCK=TRUE -DSTM32_ADC_USE_ADC3=TRUE 
 
+# USB mass storage support
+DDEFS += -DHAL_USE_COMMUNITY=TRUE -DHAL_USE_USB_MSD=TRUE
+
 # We are running on microRusEFI hardware!
 DDEFS += -DHW_MICRO_RUSEFI=1
 
diff --git a/firmware/console/binary/tunerstudio.cpp b/firmware/console/binary/tunerstudio.cpp
index 0766a48625..1b02c4c3c0 100644
--- a/firmware/console/binary/tunerstudio.cpp
+++ b/firmware/console/binary/tunerstudio.cpp
@@ -738,14 +738,15 @@ int TunerStudioBase::handleCrcCommand(ts_channel_s *tsChannel, char *data, int i
 	case TS_GET_FIRMWARE_VERSION:
 		handleGetVersion(tsChannel);
 		break;
-#if EFI_FILE_LOGGING || EFI_SIMULATOR
+#if (EFI_FILE_LOGGING && !HAL_USE_USB_MSD) || EFI_SIMULATOR
+	// This is only enabled on ECUs without USB mass storage
 	case TS_SD_R_COMMAND:
 		handleTsR(tsChannel, data);
 		break;
 	case TS_SD_W_COMMAND:
 		handleTsW(tsChannel, data);
 		break;
-#endif //EFI_FILE_LOGGING
+#endif // (EFI_FILE_LOGGING && !HAL_USE_USB_MSD)
 	case TS_GET_TEXT:
 		handleGetText(tsChannel);
 		break;
@@ -879,6 +880,7 @@ int TunerStudioBase::handleCrcCommand(ts_channel_s *tsChannel, char *data, int i
 		break;
 	}
 	default:
+		sendErrorCode(tsChannel, TS_RESPONSE_UNRECOGNIZED_COMMAND);
 		tunerStudioError("ERROR: ignoring unexpected command");
 		return false;
 	}
diff --git a/firmware/hw_layer/mmc_card.cpp b/firmware/hw_layer/mmc_card.cpp
index b1e077e197..956a1fcbf8 100644
--- a/firmware/hw_layer/mmc_card.cpp
+++ b/firmware/hw_layer/mmc_card.cpp
@@ -199,15 +199,20 @@ static void incLogFileName(void) {
 static void prepareLogFileName(void) {
 	strcpy(logName, RUSEFI_LOG_PREFIX);
 	char *ptr;
-/* TS SD protocol supports only short 8 symbol file names :(
 
+#if HAL_USE_USB_MSD
 	bool result = dateToStringShort(&logName[PREFIX_LEN]);
+#else 
+	// TS SD protocol supports only short 8 symbol file names :(
+	bool result = false;
+#endif
+
 	if (result) {
 		ptr = &logName[PREFIX_LEN + SHORT_TIME_LEN];
 	} else {
- */
 		ptr = itoa10(&logName[PREFIX_LEN], logFileIndex);
-//	}
+	}
+
 	strcat(ptr, DOT_MLG);
 }
 
diff --git a/firmware/hw_layer/mmc_card_access.cpp b/firmware/hw_layer/mmc_card_access.cpp
index 12cb878378..776d0c35d1 100644
--- a/firmware/hw_layer/mmc_card_access.cpp
+++ b/firmware/hw_layer/mmc_card_access.cpp
@@ -54,7 +54,8 @@ bool isLogFile(const char *fileName) {
 }
 #endif // EFI_FILE_LOGGING || EFI_SIMULATOR || EFI_UNIT_TEST
 
-#if EFI_FILE_LOGGING || EFI_SIMULATOR
+// Enable when logging is enabled, but not USB mass storage
+#if (EFI_FILE_LOGGING && !HAL_USE_USB_MSD) || EFI_SIMULATOR
 #include "mmc_card.h"
 
 #if EFI_SIMULATOR
@@ -378,4 +379,4 @@ void handleTsW(ts_channel_s *tsChannel, char *input) {
 	}
 }
 
-#endif // EFI_FILE_LOGGING
+#endif // (EFI_FILE_LOGGING && !HAL_USE_USB_MSD)