1 files changed, 156 insertions, 0 deletions
diff --git a/lib/lufa/Projects/XPLAINBridge/Lib/SoftUART.c b/lib/lufa/Projects/XPLAINBridge/Lib/SoftUART.c
new file mode 100644
index 000000000..5c0e3c8cd
--- /dev/null
+++ b/lib/lufa/Projects/XPLAINBridge/Lib/SoftUART.c
@@ -0,0 +1,156 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2017.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2010  David Prentice (david.prentice [at] farming [dot] uk)
+  Copyright 2010  Peter Danneger
+  Copyright 2017  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  Software UART for both data transmission and reception. This
+ *  code continuously monitors the ring buffers set up by the main
+ *  project source file and reads/writes data as it becomes available.
+ */
+
+#include "SoftUART.h"
+
+/** Total number of bits remaining to be sent in the current frame */
+static uint8_t TX_BitsRemaining;
+
+/** Temporary data variable to hold the byte being transmitted as it is shifted out */
+static uint8_t TX_Data;
+
+/** Total number of bits remaining to be received in the current frame */
+static uint8_t RX_BitsRemaining;
+
+/** Temporary data variable to hold the byte being received as it is shifted in */
+static uint8_t RX_Data;
+
+
+/** Initializes the software UART, ready for data transmission and reception into the global ring buffers. */
+void SoftUART_Init(void)
+{
+	/* Set TX pin to output high, enable RX pull-up */
+	STXPORT |= (1 << STX);
+	STXDDR  |= (1 << STX);
+	SRXPORT |= (1 << SRX);
+
+	/* Enable INT0 for the detection of incoming start bits that signal the start of a byte */
+	EICRA  = (1 << ISC01);
+	EIMSK  = (1 << INT0);
+
+	/* Set the transmission and reception timer compare values for the default baud rate */
+	SoftUART_SetBaud(9600);
+
+	/* Setup reception timer compare ISR */
+	TIMSK1 = (1 << OCIE1A);
+
+	/* Setup transmission timer compare ISR and start the timer */
+	TIMSK3 = (1 << OCIE3A);
+	TCCR3B = ((1 << CS30) | (1 << WGM32));
+}
+
+/** ISR to detect the start of a bit being sent to the software UART. */
+ISR(INT0_vect, ISR_BLOCK)
+{
+	/* Reset the number of reception bits remaining counter */
+	RX_BitsRemaining = 8;
+
+	/* Reset the bit reception timer to -(1/2) of the total bit time, so that the first data bit is
+	 * sampled mid way through the total bit time, making reception more robust.
+	 */
+	TCNT1 = -(OCR1A >> 1);
+
+	/* Check to see that the pin is still low (prevents glitches from starting a frame reception) */
+	if (!(SRXPIN & (1 << SRX)))
+	{
+		/* Disable start bit detection ISR while the next byte is received */
+		EIMSK = 0;
+
+		/* Start the reception timer */
+		TCCR1B = ((1 << CS10) | (1 << WGM12));
+	}
+}
+
+/** ISR to manage the reception of bits to the software UART. */
+ISR(TIMER1_COMPA_vect, ISR_BLOCK)
+{
+	/* Cache the current RX pin value for later checking */
+	uint8_t SRX_Cached = (SRXPIN & (1 << SRX));
+
+	/* Check if reception has finished */
+	if (RX_BitsRemaining)
+	{
+		/* Shift the current received bit mask to the next bit position */
+		RX_Data >>= 1;
+		RX_BitsRemaining--;
+
+		/* Store next bit into the received data variable */
+		if (SRX_Cached)
+		  RX_Data |= (1 << 7);
+	}
+	else
+	{
+		/* Disable the reception timer as all data has now been received, re-enable start bit detection ISR */
+		TCCR1B = 0;
+		EIFR   = (1 << INTF0);
+		EIMSK  = (1 << INT0);
+
+		/* Reception complete, store the received byte if stop bit valid */
+		if (SRX_Cached)
+		  RingBuffer_Insert(&UARTtoUSB_Buffer, RX_Data);
+	}
+}
+
+/** ISR to manage the transmission of bits via the software UART. */
+ISR(TIMER3_COMPA_vect, ISR_BLOCK)
+{
+	/* Check if transmission has finished */
+	if (TX_BitsRemaining)
+	{
+		/* Set the TX line to the value of the next bit in the byte to send */
+		if (TX_Data & (1 << 0))
+		  STXPORT &= ~(1 << STX);
+		else
+		  STXPORT |=  (1 << STX);
+
+		/* Shift the transmission byte to move the next bit into position and decrement the bits remaining counter */
+		TX_Data >>= 1;
+		TX_BitsRemaining--;
+	}
+	else if (!(RX_BitsRemaining) && !(RingBuffer_IsEmpty(&USBtoUART_Buffer)))
+	{
+		/* Start bit - TX line low */
+		STXPORT &= ~(1 << STX);
+
+		/* Transmission complete, get the next byte to send (if available) */
+		TX_Data          = ~RingBuffer_Remove(&USBtoUART_Buffer);
+		TX_BitsRemaining = 9;
+	}
+}
+