-/*\r
- LUFA Library\r
- Copyright (C) Dean Camera, 2010.\r
- \r
- dean [at] fourwalledcubicle [dot] com\r
- www.fourwalledcubicle.com\r
-*/\r
-\r
-/*\r
- Copyright 2010 David Prentice (david.prentice [at] farming [dot] uk)\r
- Copyright 2010 Peter Danneger\r
- Copyright 2010 Dean Camera (dean [at] fourwalledcubicle [dot] com)\r
-\r
- Permission to use, copy, modify, distribute, and sell this \r
- software and its documentation for any purpose is hereby granted\r
- without fee, provided that the above copyright notice appear in \r
- all copies and that both that the copyright notice and this\r
- permission notice and warranty disclaimer appear in supporting \r
- documentation, and that the name of the author not be used in \r
- advertising or publicity pertaining to distribution of the \r
- software without specific, written prior permission.\r
-\r
- The author disclaim all warranties with regard to this\r
- software, including all implied warranties of merchantability\r
- and fitness. In no event shall the author be liable for any\r
- special, indirect or consequential damages or any damages\r
- whatsoever resulting from loss of use, data or profits, whether\r
- in an action of contract, negligence or other tortious action,\r
- arising out of or in connection with the use or performance of\r
- this software.\r
-*/\r
-\r
-#include "SoftUART.h"\r
-\r
-volatile uint8_t srx_done, stx_count;\r
-volatile uint8_t srx_data, srx_mask, srx_tmp, stx_data;\r
-\r
-unsigned char SoftUART_IsReady(void)\r
-{\r
- return !(stx_count);\r
-}\r
-\r
-unsigned char SoftUART_TxByte(unsigned char c)\r
-{\r
- while (stx_count);\r
-\r
- stx_data = ~c;\r
- stx_count = 10;\r
-\r
- return c;\r
-}\r
-\r
-unsigned char SoftUART_IsReceived(void)\r
-{\r
- return srx_done;\r
-}\r
-\r
-unsigned char SoftUART_RxByte(void)\r
-{\r
- while (!(srx_done));\r
-\r
- srx_done = 0;\r
-\r
- return srx_data;\r
-}\r
-\r
-void SoftUART_Init(void)\r
-{\r
- OCR2B = TCNT2 + 1; // force first compare\r
- TCCR2A = (1 << COM2B1) | (1 << COM2B0); // T1 mode 0\r
- TCCR2B = (1 << FOC2B) | (1 << CS21); // CLK/8, T1 mode 0\r
- TIMSK2 = (1 << OCIE2B); // enable tx and wait for start\r
- EICRA = (1 << ISC01); // -ve edge\r
- EIMSK = (1 << INT0); // enable INT0 interrupt\r
-\r
- stx_count = 0; // nothing to send\r
- srx_done = 0; // nothing received\r
- STXPORT |= 1 << STX; // TX output\r
- STXDDR |= 1 << STX; // TX output\r
- SRXPORT |= (1 << SRX); // pullup on INT0\r
-}\r
-\r
-/* ISR to detect the start of a bit being sent from the transmitter. */\r
-ISR(INT0_vect)\r
-{\r
- OCR2A = TCNT2 + (BIT_TIME / 8 * 3 / 2); // scan 1.5 bits after start\r
-\r
- srx_tmp = 0; // clear bit storage\r
- srx_mask = 1; // bit mask\r
-\r
- TIFR2 = (1 << OCF2A); // clear pending interrupt\r
-\r
- if (!(SRXPIN & (1 << SRX))) // still low\r
- {\r
- TIMSK2 = (1 << OCIE2A) | (1 << OCIE2B); // wait for first bit\r
- EIMSK &= ~(1 << INT0);\r
- }\r
-}\r
-\r
-/* ISR to manage the reception of bits to the transmitter. */\r
-ISR(TIMER2_COMPA_vect)\r
-{\r
- if (srx_mask)\r
- {\r
- if (SRXPIN & (1 << SRX))\r
- srx_tmp |= srx_mask;\r
-\r
- srx_mask <<= 1;\r
-\r
- OCR2A += BIT_TIME / 8; // next bit slice\r
- }\r
- else\r
- {\r
- srx_done = 1; // mark rx data valid\r
- srx_data = srx_tmp; // store rx data\r
- TIMSK2 = (1 << OCIE2B); // enable tx and wait for start\r
- EIMSK |= (1 << INT0); // enable START irq\r
- EIFR = (1 << INTF0); // clear any pending\r
- }\r
-}\r
-\r
-/* ISR to manage the transmission of bits to the receiver. */\r
-ISR(TIMER2_COMPB_vect)\r
-{\r
- OCR2B += BIT_TIME / 8; // next bit slice\r
-\r
- if (stx_count)\r
- {\r
- if (--stx_count != 9) // no start bit\r
- {\r
- if (!(stx_data & 1)) // test inverted data\r
- TCCR2A = (1 << COM2B1) | (1 << COM2B0);\r
- else\r
- TCCR2A = (1 << COM2B1);\r
-\r
- stx_data >>= 1; // shift zero in from left\r
- }\r
- else\r
- {\r
- TCCR2A = (1 << COM2B1); // START bit\r
- }\r
- }\r
-} \r
+/*
+ LUFA Library
+ Copyright (C) Dean Camera, 2015.
+
+ dean [at] fourwalledcubicle [dot] com
+ www.lufa-lib.org
+*/
+
+/*
+ Copyright 2010 David Prentice (david.prentice [at] farming [dot] uk)
+ Copyright 2010 Peter Danneger
+ Copyright 2015 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;
+ }
+}
+
projects / pub / USBasp.git / blobdiff