From 60b30c036397cb5627fa374bb930794b225daa29 Mon Sep 17 00:00:00 2001
From: Jack Humbert <jack.humb@gmail.com>
Date: Fri, 7 Jul 2017 11:55:23 -0400
Subject: Squashed 'lib/lufa/' content from commit 385d40300
git-subtree-dir: lib/lufa
git-subtree-split: 385d4030035dbaf41591309dbde47653bd03841b
---
Projects/XPLAINBridge/Lib/SoftUART.c | 156 +++++++++++++++++++++++++++++++++++
1 file changed, 156 insertions(+)
create mode 100644 Projects/XPLAINBridge/Lib/SoftUART.c
(limited to 'Projects/XPLAINBridge/Lib/SoftUART.c')
diff --git a/Projects/XPLAINBridge/Lib/SoftUART.c b/Projects/XPLAINBridge/Lib/SoftUART.c
new file mode 100644
index 0000000000..5c0e3c8cd9
--- /dev/null
+++ b/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;
+ }
+}
+
--
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