Further improvements

Added support for expression lists (untested in standalone mode)
M23/M32 are invoked again by DSF in SBC mode
Increased SBC task priority
Bug fix: CAN diagnostics output extra NL
Bug fix: M999 P"ERASE" was not working on the Mini5+ series

17 files changed, 171 insertions, 85 deletions

diff --git a/src/CAN/CanInterface.cpp b/src/CAN/CanInterface.cpp
index 502fad4f..35ccc87e 100644
--- a/src/CAN/CanInterface.cpp
+++ b/src/CAN/CanInterface.cpp
@@ -1170,7 +1170,7 @@ void CanInterface::Diagnostics(MessageType mtype) noexcept
 		CanId id;
 		id.SetReceivedId(lastCancelledId);
 		lastCancelledId = 0;
-		str.catf(" last cancelled message type %u dest %u\n", (unsigned int)id.MsgType(), id.Dst());
+		str.catf(" last cancelled message type %u dest %u", (unsigned int)id.MsgType(), id.Dst());
 	}
 
 	reprap.GetPlatform().MessageF(mtype, "Tx timeouts%s\n", str.c_str());
diff --git a/src/Configuration.h b/src/Configuration.h
index dd67344f..efdd6141 100644
--- a/src/Configuration.h
+++ b/src/Configuration.h
@@ -377,6 +377,7 @@ static_assert(MaxExpectedWebDirFilenameLength + strlen(WEB_DIR) + strlen(".gz")
 #define EOF_STRING "<!-- **EoF** -->"
 
 // List defaults
+constexpr char EXPRESSION_LIST_SEPARATOR = ',';
 constexpr char LIST_SEPARATOR = ':';
 
 #endif
diff --git a/src/GCodes/GCodeBuffer/BinaryParser.cpp b/src/GCodes/GCodeBuffer/BinaryParser.cpp
index 78145ef1..de4b7b02 100644
--- a/src/GCodes/GCodeBuffer/BinaryParser.cpp
+++ b/src/GCodes/GCodeBuffer/BinaryParser.cpp
@@ -457,17 +457,17 @@ void BinaryParser::GetPossiblyQuotedString(const StringRef& str, bool allowEmpty
 
 void BinaryParser::GetFloatArray(float arr[], size_t& length, bool doPad) THROWS(GCodeException)
 {
-	GetArray(arr, length, doPad);
+	GetArray(arr, length, doPad, DataType::Float);
 }
 
 void BinaryParser::GetIntArray(int32_t arr[], size_t& length, bool doPad) THROWS(GCodeException)
 {
-	GetArray(arr, length, doPad);
+	GetArray(arr, length, doPad, DataType::Int);
 }
 
 void BinaryParser::GetUnsignedArray(uint32_t arr[], size_t& length, bool doPad) THROWS(GCodeException)
 {
-	GetArray(arr, length, doPad);
+	GetArray(arr, length, doPad, DataType::UInt);
 }
 
 // Get a :-separated list of drivers after a key letter
@@ -498,6 +498,17 @@ void BinaryParser::GetDriverIdArray(DriverId arr[], size_t& length) THROWS(GCode
 		length = seenParameter->intValue;
 		break;
 
+	case DataType::Expression:
+	{
+		float temp[seenParameter->intValue];
+		GetArray(temp, length, false, DataType::Float);
+		for (int i = 0; i < seenParameter->intValue; i++)
+		{
+			SetDriverIdFromBinary(arr[i], temp[i]);
+		}
+		break;
+	}
+
 	default:
 		length = 0;
 		return;
@@ -562,7 +573,7 @@ void BinaryParser::AppendFullCommand(const StringRef &s) const noexcept
 	}
 }
 
-template<typename T> void BinaryParser::GetArray(T arr[], size_t& length, bool doPad) THROWS(GCodeException)
+template<typename T> void BinaryParser::GetArray(T arr[], size_t& length, bool doPad, DataType type) THROWS(GCodeException)
 {
 	if (seenParameter == nullptr)
 	{
@@ -617,34 +628,104 @@ template<typename T> void BinaryParser::GetArray(T arr[], size_t& length, bool d
 		break;
 
 	case DataType::Expression:
-		//TODO need a way to pass multi-element array-valued expressions. For now we support only single-element expressions.
+	{
+		const char *pos = seenParameterValue, *endPos = seenParameterValue + seenParameter->intValue;
+
+		// Check if the whole expression is encapsulated in curly braces and remove them if necessary
+		if (*pos == '{' && pos != endPos)
 		{
-			ExpressionParser parser(gb, seenParameterValue, seenParameterValue + seenParameter->intValue, -1);
-			const ExpressionValue val = parser.Parse();
-			switch ((TypeCode)val.type)
+			bool isEncapsulated = true, inQuotes = false;
+			size_t numBraces = 1;
+			for (const char *str = pos + 1; str < endPos; str++)
+			{
+				if (inQuotes)
+				{
+					inQuotes = (*str != '"');
+				}
+				else if (*str == '"')
+				{
+					inQuotes = true;
+				}
+				else if (*str == '{')
+				{
+					numBraces++;
+				}
+				else if (*str == '}')
+				{
+					numBraces--;
+					if (numBraces == 0)
+					{
+						const char *curPos = str;
+						while (str != endPos && strchr("\t ", *++str) != nullptr) { }
+						if (str == endPos)
+						{
+							endPos = curPos + 1;
+						}
+						else
+						{
+							isEncapsulated = false;
+						}
+						break;
+					}
+				}
+			}
+
+			if (isEncapsulated)
 			{
-			case TypeCode::Int32:
-				arr[0] = (T)val.iVal;
-				lastIndex = 0;
+				pos++;
+				endPos--;
+			}
+		}
+
+		// Read array expression
+		for (;;)
+		{
+			if (lastIndex >= (int)length)
+			{
+				throw ConstructParseException("array too long, max length = %u", (uint32_t)length);
+			}
+
+			// Read the next expression value
+			ExpressionParser parser(gb, pos, endPos, -1);
+			switch (type)
+			{
+			case DataType::Int:
+				arr[++lastIndex] = (T)parser.ParseInteger();
 				break;
 
-			case TypeCode::Float:
-				arr[0] = (T)val.fVal;
-				lastIndex = 0;
+			case DataType::UInt:
+				arr[++lastIndex] = (T)parser.ParseUnsigned();
 				break;
 
-			case TypeCode::Uint32:
-			case TypeCode::DriverId:
-				arr[0] = (T)val.uVal;
-				lastIndex = 0;
+			case DataType::Float:
+				arr[++lastIndex] = (T)parser.ParseFloat();
 				break;
 
 			default:
-				throw ConstructParseException("invalid expression type");
+				throw ConstructParseException("Unsupported array data type");
+			}
+			parser.CheckForExtraCharacters(true);
+			pos = parser.GetEndptr();
+
+			if (pos++ >= endPos)
+			{
+				break;
+			}
+		}
+
+		if (doPad && lastIndex == 0)
+		{
+			for (size_t i = 1; i < length; i++)
+			{
+				arr[i] = arr[0];
 			}
-			parser.CheckForExtraCharacters();
+		}
+		else
+		{
+			length = lastIndex + 1;
 		}
 		break;
+	}
 
 	default:
 		length = 0;
diff --git a/src/GCodes/GCodeBuffer/BinaryParser.h b/src/GCodes/GCodeBuffer/BinaryParser.h
index 5a4bcc38..3495d9c8 100644
--- a/src/GCodes/GCodeBuffer/BinaryParser.h
+++ b/src/GCodes/GCodeBuffer/BinaryParser.h
@@ -72,7 +72,7 @@ private:
 	GCodeException ConstructParseException(const char *str, uint32_t param) const noexcept;
 
 	size_t AddPadding(size_t bytesRead) const noexcept { return (bytesRead + 3u) & (~3u); }
-	template<typename T> void GetArray(T arr[], size_t& length, bool doPad) THROWS(GCodeException) SPEED_CRITICAL;
+	template<typename T> void GetArray(T arr[], size_t& length, bool doPad, DataType type) THROWS(GCodeException) SPEED_CRITICAL;
 	void WriteParameters(const StringRef& s, bool quoteStrings) const noexcept;
 
 	size_t bufferLength;
diff --git a/src/GCodes/GCodeBuffer/ExpressionParser.cpp b/src/GCodes/GCodeBuffer/ExpressionParser.cpp
index 133ed763..0e3ac432 100644
--- a/src/GCodes/GCodeBuffer/ExpressionParser.cpp
+++ b/src/GCodes/GCodeBuffer/ExpressionParser.cpp
@@ -713,10 +713,12 @@ void ExpressionParser::SkipWhiteSpace() noexcept
 	}
 }
 
-void ExpressionParser::CheckForExtraCharacters() THROWS(GCodeException)
+void ExpressionParser::CheckForExtraCharacters(bool isArrayExpression) THROWS(GCodeException)
 {
 	SkipWhiteSpace();
-	if (CurrentCharacter() != 0)
+
+	char c = CurrentCharacter();
+	if (c != 0 && (!isArrayExpression || (c != EXPRESSION_LIST_SEPARATOR && c != LIST_SEPARATOR)))
 	{
 		ThrowParseException("Unexpected characters after expression");
 	}
diff --git a/src/GCodes/GCodeBuffer/ExpressionParser.h b/src/GCodes/GCodeBuffer/ExpressionParser.h
index fc8dc1b3..bfd4de4e 100644
--- a/src/GCodes/GCodeBuffer/ExpressionParser.h
+++ b/src/GCodes/GCodeBuffer/ExpressionParser.h
@@ -26,7 +26,7 @@ public:
 	uint32_t ParseUnsigned() THROWS(GCodeException);
 
 	void SkipWhiteSpace() noexcept;
-	void CheckForExtraCharacters() THROWS(GCodeException);
+	void CheckForExtraCharacters(bool isArrayExpression = false) THROWS(GCodeException);
 	const char *GetEndptr() const noexcept { return currentp; }
 
 private:
diff --git a/src/GCodes/GCodeBuffer/StringParser.cpp b/src/GCodes/GCodeBuffer/StringParser.cpp
index 691be0ac..9247c577 100644
--- a/src/GCodes/GCodeBuffer/StringParser.cpp
+++ b/src/GCodes/GCodeBuffer/StringParser.cpp
@@ -1086,7 +1086,7 @@ void StringParser::GetFloatArray(float arr[], size_t& returnedLength, bool doPad
 	{
 		CheckArrayLength(length, returnedLength);
 		arr[length++] = ReadFloatValue();
-		if (gb.buffer[readPointer] != LIST_SEPARATOR)
+		if (gb.buffer[readPointer] != EXPRESSION_LIST_SEPARATOR && gb.buffer[readPointer] != LIST_SEPARATOR)
 		{
 			break;
 		}
@@ -1123,7 +1123,7 @@ void StringParser::GetIntArray(int32_t arr[], size_t& returnedLength, bool doPad
 		CheckArrayLength(length, returnedLength);
 		arr[length] = ReadIValue();
 		length++;
-		if (gb.buffer[readPointer] != LIST_SEPARATOR)
+		if (gb.buffer[readPointer] != EXPRESSION_LIST_SEPARATOR && gb.buffer[readPointer] != LIST_SEPARATOR)
 		{
 			break;
 		}
@@ -1159,7 +1159,7 @@ void StringParser::GetUnsignedArray(uint32_t arr[], size_t& returnedLength, bool
 		CheckArrayLength(length, returnedLength);
 		arr[length] = ReadUIValue();
 		length++;
-		if (gb.buffer[readPointer] != LIST_SEPARATOR)
+		if (gb.buffer[readPointer] != EXPRESSION_LIST_SEPARATOR && gb.buffer[readPointer] != LIST_SEPARATOR)
 		{
 			break;
 		}
@@ -1196,7 +1196,7 @@ void StringParser::GetDriverIdArray(DriverId arr[], size_t& returnedLength) THRO
 		CheckArrayLength(length, returnedLength);
 		arr[length] = ReadDriverIdValue();
 		length++;
-		if (gb.buffer[readPointer] != LIST_SEPARATOR)
+		if (gb.buffer[readPointer] != EXPRESSION_LIST_SEPARATOR && gb.buffer[readPointer] != LIST_SEPARATOR)
 		{
 			break;
 		}
diff --git a/src/GCodes/GCodes.cpp b/src/GCodes/GCodes.cpp
index 1a932bd0..9c716f3b 100644
--- a/src/GCodes/GCodes.cpp
+++ b/src/GCodes/GCodes.cpp
@@ -478,16 +478,10 @@ void GCodes::Spin() noexcept
 
 
 #if HAS_LINUX_INTERFACE
-	if (reprap.UsingLinuxInterface())
+	// Need to check if the print has been stopped by the SBC
+	if (reprap.UsingLinuxInterface() && reprap.GetLinuxInterface().HasPrintStopped())
 	{
-		if (reprap.GetLinuxInterface().HasPrintStarted())
-		{
-			StartPrinting(true);
-		}
-		else if (reprap.GetLinuxInterface().HasPrintStopped())
-		{
-			StopPrint(reprap.GetLinuxInterface().GetPrintStopReason());
-		}
+		StopPrint(reprap.GetLinuxInterface().GetPrintStopReason());
 	}
 #endif
 
diff --git a/src/GCodes/GCodes2.cpp b/src/GCodes/GCodes2.cpp
index 894630b0..d5dc4af4 100644
--- a/src/GCodes/GCodes2.cpp
+++ b/src/GCodes/GCodes2.cpp
@@ -831,7 +831,9 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeEx
 					result = MassStorage::Unmount(card, reply);
 				}
 				break;
+#endif
 
+#if HAS_MASS_STORAGE || HAS_LINUX_INTERFACE
 			case 23: // Set file to print
 			case 32: // Select file and start SD print
 				// We now allow a file that is being printed to chain to another file. This is required for the resume-after-power-fail functionality.
@@ -849,7 +851,17 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeEx
 				{
 					String<MaxFilenameLength> filename;
 					gb.GetUnprecedentedString(filename.GetRef());
-					if (QueueFileToPrint(filename.c_str(), reply))
+					if (
+#if HAS_LINUX_INTERFACE
+						reprap.UsingLinuxInterface()
+# if HAS_MASS_STORAGE
+						||
+# endif
+#endif
+#if HAS_MASS_STORAGE
+						QueueFileToPrint(filename.c_str(), reply)
+#endif
+					   )
 					{
 						reprap.GetPrintMonitor().StartingPrint(filename.c_str());
 						if (gb.LatestMachineState().compatibility == Compatibility::Marlin)
diff --git a/src/GCodes/GCodes3.cpp b/src/GCodes/GCodes3.cpp
index 3f991bf0..5bed126e 100644
--- a/src/GCodes/GCodes3.cpp
+++ b/src/GCodes/GCodes3.cpp
@@ -432,13 +432,7 @@ GCodeResult GCodes::SimulateFile(GCodeBuffer& gb, const StringRef &reply, const
 		simulationMode = 1;
 		reprap.GetMove().Simulate(simulationMode);
 		reprap.GetPrintMonitor().StartingPrint(file.c_str());
-# if HAS_LINUX_INTERFACE
-		if (!reprap.UsingLinuxInterface())
-# endif
-		{
-			// If using a SBC, this is already called when the print file info is set
-			StartPrinting(true);
-		}
+		StartPrinting(true);
 		reply.printf("Simulating print of file %s", file.c_str());
 		return GCodeResult::ok;
 	}
diff --git a/src/Hardware/ExceptionHandlers.cpp b/src/Hardware/ExceptionHandlers.cpp
index 640c0a41..1413108d 100644
--- a/src/Hardware/ExceptionHandlers.cpp
+++ b/src/Hardware/ExceptionHandlers.cpp
@@ -15,6 +15,12 @@
 # include <Reset.h>
 #endif
 
+#if SAME5x
+// Magic address and value to launch the uf2 bootloader on failure, see inc/uf2.h in uf2-samdx1 repository
+# define DBL_TAP_PTR ((volatile uint32_t *)(HSRAM_ADDR + HSRAM_SIZE - 4))
+# define DBL_TAP_MAGIC 0xf01669ef // Randomly selected, adjusted to have first and last bit set
+#endif
+
 // Perform a software reset. 'stk' points to the exception stack (r0 r1 r2 r3 r12 lr pc xPSR) if the cause is an exception, otherwise it is nullptr.
 [[noreturn]] void SoftwareReset(SoftwareResetReason initialReason, const uint32_t *stk) noexcept
 {
@@ -31,7 +37,8 @@
 	if (initialReason == SoftwareResetReason::erase)
 	{
 #if SAME5x
-		//TODO invalidate flash so the USB bootloader runs
+		// Start from uf2 bootloader next time. This pretends the reset button has been pressed twice in short succession
+		*DBL_TAP_PTR = DBL_TAP_MAGIC;
 #else
 		EraseAndReset();
 #endif
diff --git a/src/Linux/DataTransfer.cpp b/src/Linux/DataTransfer.cpp
index 69c09cd9..bd1312fa 100644
--- a/src/Linux/DataTransfer.cpp
+++ b/src/Linux/DataTransfer.cpp
@@ -304,7 +304,7 @@ pre(bytesToTransfer <= inBuffer.limit; bytesToTransfer <= outBuffer.limit)
 
 	// Enable SPI and notify the SBC we are ready
 #if SAME5x
-	SbcSpiSercom->SPI.INTFLAG.reg = 0xFF;			// clear any pending interrupts
+	SbcSpiSercom->SPI.INTFLAG.reg = 0xFF;						// clear any pending interrupts
 	SbcSpiSercom->SPI.INTENSET.reg = SERCOM_SPI_INTENSET_SSL;	// enable the start of transfer (SS low) interrupt
 	SbcSpiSercom->SPI.CTRLA.reg |= SERCOM_SPI_CTRLA_ENABLE;
 	while (SbcSpiSercom->SPI.SYNCBUSY.reg & (SERCOM_SPI_SYNCBUSY_SWRST | SERCOM_SPI_SYNCBUSY_ENABLE)) { };
@@ -494,9 +494,9 @@ void DataTransfer::Init() noexcept
 	}
 }
 
-void DataTransfer::SetSBCTask(TaskHandle handle) noexcept
+void DataTransfer::InitFromTask() noexcept
 {
-	linuxTaskHandle = handle;
+	linuxTaskHandle = TaskBase::GetCallerTaskHandle();
 }
 
 void DataTransfer::Diagnostics(MessageType mtype) noexcept
diff --git a/src/Linux/DataTransfer.h b/src/Linux/DataTransfer.h
index cf1d47d6..c7f9fa2d 100644
--- a/src/Linux/DataTransfer.h
+++ b/src/Linux/DataTransfer.h
@@ -30,7 +30,7 @@ class DataTransfer
 public:
 	DataTransfer() noexcept;
 	void Init() noexcept;
-	void SetSBCTask(TaskHandle handle) noexcept;
+	void InitFromTask() noexcept;
 	void Diagnostics(MessageType mtype) noexcept;
 
 	bool IsConnected() const noexcept;														// Check if the connection to DCS is live
diff --git a/src/Linux/LinuxInterface.cpp b/src/Linux/LinuxInterface.cpp
index c442ffa5..9469c139 100644
--- a/src/Linux/LinuxInterface.cpp
+++ b/src/Linux/LinuxInterface.cpp
@@ -39,6 +39,7 @@ constexpr size_t SBCTaskStackWords = 1000;			// debug builds use more stack
 #else
 constexpr size_t SBCTaskStackWords = 820;
 #endif
+constexpr uint32_t LinuxYieldTimeout = 10;
 
 static Task<SBCTaskStackWords> *sbcTask;
 
@@ -49,7 +50,7 @@ extern "C" [[noreturn]] void SBCTaskStart(void * pvParameters) noexcept
 
 LinuxInterface::LinuxInterface() noexcept : isConnected(false), numDisconnects(0), numTimeouts(0),
 	maxDelayBetweenTransfers(SpiTransferDelay), numMaxEvents(SpiEventsRequired), delaying(false), numEvents(0),
-	reportPause(false), reportPauseWritten(false), printStarted(false), printStopped(false),
+	reportPause(false), reportPauseWritten(false), printStopped(false),
 	codeBuffer(nullptr), rxPointer(0), txPointer(0), txEnd(0), sendBufferUpdate(true), iapWritePointer(IAP_IMAGE_START),
 	waitingForFileChunk(false), fileMutex(), fileSemaphore(), fileOperation(FileOperation::none), fileOperationPending(false)
 #ifdef TRACK_FILE_CODES
@@ -94,12 +95,12 @@ void LinuxInterface::Spin() noexcept
 
 [[noreturn]] void LinuxInterface::TaskLoop() noexcept
 {
-	transfer.SetSBCTask(sbcTask);
+	transfer.InitFromTask();
 	transfer.StartNextTransfer();
-	bool writingIap = false, hadReset = false, skipNextDelay = false;
+
+	bool writingIap = false, isReady = false, hadReset = false, skipNextDelay = false;
 	for (;;)
 	{
-		bool isReady = false;
 		if (hadReset)
 		{
 			isReady = true;
@@ -110,6 +111,10 @@ void LinuxInterface::Spin() noexcept
 			isReady = true;
 			hadReset = isConnected && transfer.LinuxHadReset();
 		}
+		else
+		{
+			isReady = false;
+		}
 
 		if (isReady && !hadReset)
 		{
@@ -280,7 +285,6 @@ void LinuxInterface::Spin() noexcept
 					String<MaxFilenameLength> filename;
 					transfer.ReadPrintStartedInfo(packet->length, filename.GetRef(), fileInfo);
 					reprap.GetPrintMonitor().SetPrintingFileInfo(filename.c_str(), fileInfo);
-					printStarted = true;
 					break;
 				}
 
@@ -292,7 +296,7 @@ void LinuxInterface::Spin() noexcept
 					{
 						// Just mark the print file as finished
 						GCodeBuffer * const gb = reprap.GetGCodes().GetGCodeBuffer(GCodeChannel::File);
-						MutexLocker locker(gb->mutex, 10);
+						MutexLocker locker(gb->mutex, LinuxYieldTimeout);
 						if (locker)
 						{
 							gb->SetPrintFinished();
@@ -330,7 +334,7 @@ void LinuxInterface::Spin() noexcept
 						}
 						else
 						{
-							MutexLocker locker(gb->mutex, 10);
+							MutexLocker locker(gb->mutex, LinuxYieldTimeout);
 							if (locker)
 							{
 								if (error)
@@ -408,7 +412,7 @@ void LinuxInterface::Spin() noexcept
 					if (channel.IsValid())
 					{
 						GCodeBuffer * const gb = reprap.GetGCodes().GetGCodeBuffer(channel);
-						MutexLocker locker(gb->mutex, 10);
+						MutexLocker locker(gb->mutex, LinuxYieldTimeout);
 						if (locker && reprap.GetGCodes().LockMovementAndWaitForStandstill(*gb))
 						{
 							transfer.WriteLocked(channel);
@@ -432,7 +436,7 @@ void LinuxInterface::Spin() noexcept
 					if (channel.IsValid())
 					{
 						GCodeBuffer * const gb = reprap.GetGCodes().GetGCodeBuffer(channel);
-						MutexLocker locker(gb->mutex, 10);
+						MutexLocker locker(gb->mutex, LinuxYieldTimeout);
 						if (locker)
 						{
 							reprap.GetGCodes().UnlockAll(*gb);
@@ -523,7 +527,7 @@ void LinuxInterface::Spin() noexcept
 						try
 						{
 							// Evaluate the expression and send the result to DSF
-							MutexLocker lock(gb->mutex, 10);
+							MutexLocker lock(gb->mutex, LinuxYieldTimeout);
 							if (lock)
 							{
 								ExpressionParser parser(*gb, expression.c_str(), expression.c_str() + expression.strlen());
@@ -620,7 +624,7 @@ void LinuxInterface::Spin() noexcept
 							gb->ResolveMacroRequest(true, false);
 						}
 
-						MutexLocker locker(gb->mutex, 10);
+						MutexLocker locker(gb->mutex, LinuxYieldTimeout);
 						if (locker)
 						{
 							// Note that we do not call StopPrint here or set any other variables; DSF already does that
@@ -654,7 +658,7 @@ void LinuxInterface::Spin() noexcept
 					}
 
 					GCodeBuffer * const gb = reprap.GetGCodes().GetGCodeBuffer(channel);
-					MutexLocker lock(gb->mutex, 10);
+					MutexLocker lock(gb->mutex, LinuxYieldTimeout);
 					if (!lock)
 					{
 						packetAcknowledged = false;
@@ -734,7 +738,7 @@ void LinuxInterface::Spin() noexcept
 					}
 
 					GCodeBuffer * const gb = reprap.GetGCodes().GetGCodeBuffer(channel);
-					MutexLocker lock(gb->mutex, 10);
+					MutexLocker lock(gb->mutex, LinuxYieldTimeout);
 					if (!lock)
 					{
 						packetAcknowledged = false;
@@ -865,8 +869,6 @@ void LinuxInterface::Spin() noexcept
 			if (!writingIap && !skipNextDelay && numEvents < numMaxEvents && !waitingForFileChunk &&
 				!fileOperationPending && (fileOperation != FileOperation::write || numFileWriteRequests == 0))
 			{
-				TaskBase::ClearNotifyCount();
-
 				delaying = true;
 				if (!TaskBase::Take(maxDelayBetweenTransfers))
 				{
@@ -901,7 +903,7 @@ void LinuxInterface::Spin() noexcept
 				sendBufferUpdate = !transfer.WriteCodeBufferUpdate(bufferSpace);
 			}
 
-			if (!writingIap)					// it's not safe to access GCodes once we have started writing the IAP
+			if (!writingIap)					// it's not safe to access other resources once we have started writing the IAP
 			{
 				// Get another chunk of the file being requested
 				if (waitingForFileChunk &&
@@ -1010,7 +1012,7 @@ void LinuxInterface::Spin() noexcept
 					// Deal with other requests unless we are still waiting in a semaphore
 					if (!gb->IsWaitingForMacro())
 					{
-						MutexLocker gbLock(gb->mutex, 10);
+						MutexLocker gbLock(gb->mutex, LinuxYieldTimeout);
 						if (gbLock)
 						{
 							if (gb->GetChannel() != GCodeChannel::Daemon)
@@ -1080,7 +1082,7 @@ void LinuxInterface::Spin() noexcept
 				if (reportPause)
 				{
 					GCodeBuffer * const fileGCode = reprap.GetGCodes().GetGCodeBuffer(GCodeChannel::File);
-					MutexLocker locker(fileGCode->mutex, 10);
+					MutexLocker locker(fileGCode->mutex, LinuxYieldTimeout);
 					if (locker && transfer.WritePrintPaused(pauseFilePosition, pauseReason))
 					{
 						fileGCode->Invalidate();
@@ -1157,7 +1159,7 @@ void LinuxInterface::Spin() noexcept
 			if (hadReset)
 			{
 				// Let the main task invalidate resources
-				RTOSIface::Yield();
+				TaskBase::Take(LinuxYieldTimeout);
 			}
 			else
 			{
@@ -1168,6 +1170,11 @@ void LinuxInterface::Spin() noexcept
 		else if (!writingIap)
 		{
 			// A transfer is being performed but it has not finished yet
+			TaskBase::Take(LinuxYieldTimeout);
+		}
+		else
+		{
+			// IAP binary is being written, only keep equal or higher priority tasks running
 			RTOSIface::Yield();
 		}
 	}
diff --git a/src/Linux/LinuxInterface.h b/src/Linux/LinuxInterface.h
index b28d88d2..74936723 100644
--- a/src/Linux/LinuxInterface.h
+++ b/src/Linux/LinuxInterface.h
@@ -46,7 +46,6 @@ public:
 	void EventOccurred(bool timeCritical = false) noexcept;						// Called when a new event has happened. It can optionally start off a new transfer immediately
 	GCodeResult HandleM576(GCodeBuffer& gb, const StringRef& reply) noexcept;	// Set the SPI communication parameters
 
-	bool HasPrintStarted();
 	bool HasPrintStopped();
 	StopPrintReason GetPrintStopReason() const { return printStopReason; }
 	bool FillBuffer(GCodeBuffer &gb) noexcept;									// Try to fill up the G-code buffer with the next available G-code
@@ -80,7 +79,7 @@ private:
 	GCodeFileInfo fileInfo;
 	FilePosition pauseFilePosition;
 	PrintPausedReason pauseReason;
-	bool reportPause, reportPauseWritten, printStarted, printStopped;
+	bool reportPause, reportPauseWritten, printStopped;
 	StopPrintReason printStopReason;
 
 	char *codeBuffer;
@@ -147,17 +146,6 @@ inline void LinuxInterface::SetPauseReason(FilePosition position, PrintPausedRea
 	reportPause = true;
 }
 
-inline bool LinuxInterface::HasPrintStarted()
-{
-	TaskCriticalSectionLocker locker;
-	if (printStarted)
-	{
-		printStarted = false;
-		return true;
-	}
-	return false;
-}
-
 inline bool LinuxInterface::HasPrintStopped()
 {
 	TaskCriticalSectionLocker locker;
diff --git a/src/Platform/TaskPriorities.h b/src/Platform/TaskPriorities.h
index 36545a55..a30743c0 100644
--- a/src/Platform/TaskPriorities.h
+++ b/src/Platform/TaskPriorities.h
@@ -14,7 +14,7 @@ namespace TaskPriority
 	constexpr int IdlePriority = 0;
 	constexpr int SpinPriority = 1;							// priority for tasks that rarely block
 #if HAS_LINUX_INTERFACE
-	constexpr int SbcPriority = 1;							// priority for SBC task. TODO increase this when we are certain that it never spins.
+	constexpr int SbcPriority = 2;							// priority for SBC task
 #endif
 #if defined(LPC_NETWORKING)
     constexpr int TcpPriority  = 2;
diff --git a/src/PrintMonitor/PrintMonitor.cpp b/src/PrintMonitor/PrintMonitor.cpp
index 925897fd..07a4dae3 100644
--- a/src/PrintMonitor/PrintMonitor.cpp
+++ b/src/PrintMonitor/PrintMonitor.cpp
@@ -292,11 +292,11 @@ void PrintMonitor::StartingPrint(const char* filename) noexcept
 #if HAS_MASS_STORAGE
 	WriteLocker locker(printMonitorLock);
 	MassStorage::CombineName(filenameBeingPrinted.GetRef(), platform.GetGCodeDir(), filename);
-	printingFileParsed = false;
 # if HAS_LINUX_INTERFACE
 	if (!reprap.UsingLinuxInterface())
 # endif
 	{
+		printingFileParsed = false;
 		if (MassStorage::GetFileInfo(filenameBeingPrinted.c_str(), printingFileInfo, false) != GCodeResult::notFinished)
 		{
 			UpdatePrintingFileInfo();