--- /dev/null
+
+PROGRAM=scxreader
+SRC=scxreader.c uart.c version.c
+OBJ=$(SRC:.c=.o)
+
+
+MCU=atmega328p
+# AVRDUDE_MCU=$(MCU)
+AVRDUDE_MCU=atmega328p
+AVRDUDE_PROGRAMMER=arduino
+
+CFLAGS=-Wall -Os -mmcu=$(MCU) -DUSE_LOGGING=1 -DF_CPU=16000000UL -std=gnu99
+LDFLAGS=
+AVRDUDE_FLAGS= -p$(AVRDUDE_MCU) -c $(AVRDUDE_PROGRAMMER) -P /dev/ttyUSB0 -b 57600
+
+FORMAT=ihex
+
+CC=avr-gcc
+OBJCOPY=avr-objcopy
+OBJDUMP=avr-objdump
+AVRDUDE=avrdude
+
+all: $(PROGRAM).hex $(PROGRAM).eep
+
+program: $(PROGRAM).hex $(PROGRAM).eep
+ $(AVRDUDE) $(AVRDUDE_FLAGS) -U flash:w:$(PROGRAM).hex:i -U eeprom:w:$(PROGRAM).eep:i
+
+program_flash: $(PROGRAM).hex
+ $(AVRDUDE) $(AVRDUDE_FLAGS) -U flash:w:$(PROGRAM).hex:i
+
+program_eeprom: $(PROGRAM).eep
+ $(AVRDUDE) $(AVRDUDE_FLAGS) eeprom:w:$(PROGRAM).eep:i
+
+dump_eeprom:
+ $(AVRDUDE) $(AVRDUDE_FLAGS) -U eeprom:r:eeprom.raw:r
+ od -tx1 eeprom.raw
+
+objdump: $(PROGRAM).elf
+ $(OBJDUMP) --disassemble $<
+
+.PRECIOUS : $(OBJ) $(PROGRAM).elf
+
+%.hex: %.elf
+ $(OBJCOPY) -O $(FORMAT) -R .eeprom $< $@
+
+%.eep: %.elf
+ $(OBJCOPY) -j .eeprom --set-section-flags=.eeprom="alloc,load" \
+ --change-section-lma .eeprom=0 -O $(FORMAT) $< $@
+
+%.elf: $(OBJ)
+ $(CC) $(CFLAGS) $(OBJ) -o $@ $(LDFLAGS)
+
+%.o: %.c lights.h Makefile
+ $(CC) -c $(CFLAGS) $< -o $@
+
+%.s: %.c lights.h Makefile
+ $(CC) -S -c $(CFLAGS) $< -o $@
+
+%.o: %.S
+ $(CC) -c $(CFLAGS) $< -o $@
+
+clean:
+ rm -f $(PROGRAM).hex $(PROGRAM).eep $(PROGRAM).elf *.o *.s eeprom.raw \
+ version.c
+
+version.c:
+ ./version.pl > version.c
+
+.PHONY: all clean dump_eeprom program program_flash program_eeprom objdump \
+ version.c
+
+
--- /dev/null
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+#include <util/delay.h>
+
+#include "uart.h"
+
+// which pin is the zener diode connected to
+#define read_scx_pin() (PINB & _BV(PB2))
+
+// how many consecutive readings have to be the same in order to
+// accept the pin value
+#define DENOISE_COUNT 4
+
+#ifndef F_CPU
+#error "F_CPU not defined. Set F_CPU in Makefile."
+#endif
+
+#define STEP (F_CPU/115200) // duration of one bit
+#define BYTE_PAUSE_MAX (20*STEP) // inter-packet length threshold
+
+void tc1_init()
+{
+ TCNT1 = 0;
+ TCCR1B = _BV(CS10); // run at F_CPU clock, no prescaling
+}
+
+// read the value until it is stable, i.e. until DENOISE_COUNT consecutive
+// readings give the same value
+static unsigned char read_scx_pin_denoised()
+{
+ unsigned char prev, count;
+
+ count = 0;
+ prev = read_scx_pin();
+
+ while (count < DENOISE_COUNT) {
+ unsigned char curr = read_scx_pin();
+ if (curr != prev) {
+ count = 0;
+ prev = curr;
+ } else {
+ ++count;
+ }
+ }
+ return prev;
+}
+
+// how long we waited for the start bit
+static unsigned char long_byte_wait;
+
+static unsigned char read_scx_byte()
+{
+ unsigned short curr_time, prev_time, interval;
+ unsigned char data, i, toolong = 0, step;
+
+retry:
+ // wait for 0, distinguish between inter- and intra-packet wait times
+ prev_time = TCNT1;
+
+ long_byte_wait = 0;
+ while (read_scx_pin_denoised()) {
+ curr_time = TCNT1;
+ if (curr_time - prev_time > BYTE_PAUSE_MAX)
+ long_byte_wait = 1;
+ }
+
+ ATOMIC_BLOCK(ATOMIC_FORCEON) {
+ // wait for 1 (end of the first start-bit),
+ // remember the length of the start bit
+ // in order to distinguish between car and other packets
+ prev_time = curr_time = TCNT1;
+ interval = 0;
+
+ while (!read_scx_pin_denoised()) { // wait for 1
+ curr_time = TCNT1;
+ interval = curr_time - prev_time;
+
+ if (interval >= 4*STEP) { // start bit too long
+ if (!toolong) {
+ uart_tx_byte(0x12, 0);
+ toolong = 1;
+ }
+ goto retry;
+ }
+ };
+
+ toolong = 0;
+
+ // start bit too short
+ if (interval < 3*STEP/4) {
+ uart_tx_byte(0x10, 0);
+ goto retry;
+ }
+
+ // car packets are at 57600 baud, start bit is twice as long
+ step = interval > (3*STEP/2) ? 2*STEP : STEP;
+
+ // advance into the middle of the next bit
+ curr_time += step / 2;
+
+ // start bit detected, now read the eight data bits
+ data = 0;
+ for (i = 0; i < 8; i++) {
+ data >>= 1;
+ while (TCNT1 - curr_time < step)
+ ;
+ data |= read_scx_pin_denoised() ? 0x80 : 0;
+ curr_time += step;
+ }
+
+ // read stop bit
+ while (TCNT1 - curr_time < step)
+ ;
+
+ if (!read_scx_pin_denoised()) // no stop bit?
+ uart_tx_byte(0x13, 0); // report error, but return data anyway
+ }; // ATOMIC
+ return data;
+}
+
+extern unsigned char version[], version_len;
+
+static void print_version()
+{
+ unsigned char i;
+
+ for (i = 0; i < version_len; i++)
+ uart_tx_byte(version[i], 0);
+}
+
+int main()
+{
+ unsigned char count = 0, pkt_len = 0;
+
+ uart_init();
+ tc1_init();
+
+ sei();
+
+ _delay_ms(1000);
+ print_version();
+ _delay_ms(500);
+
+ // main loop
+ while (1) {
+ unsigned char byte = read_scx_byte();
+
+ uart_tx_byte(byte, 0);
+
+ count++;
+ count &= 0x7F; // avoid overflow
+
+ // try to synchronize with the packet start
+ // - we need this in order to determine the packet length
+ // and in order to add 0x05 end byte after the packet
+ if (byte == 0x55 && long_byte_wait)
+ count = 1;
+
+ if (count == 2) {
+ if (byte >= 0x40 && byte <= 0x45) { // car pkt
+ pkt_len = 5;
+ } else {
+ pkt_len = 9;
+ }
+ }
+
+ if (count == pkt_len) {
+ uart_tx_byte(0x05, 0); // SEB interface compatibility
+ count = 0;
+ }
+ }
+ // NOTREACHED
+}
+
--- /dev/null
+/*
+ * Minimalistic TX-only compile-time configured asynchronous buffered
+ * UART communication for Arduino Nano (Atmega 88/168/328).
+ */
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+#include <util/delay.h>
+
+// user settable parameters start
+#define UART_BAUD 115200
+#define TX_BUFFER (1 << 4) // this has to be a power of two
+// user settable parameters end
+
+#define TX_BUFFER_MASK (TX_BUFFER-1)
+
+#if (TX_BUFFER & TX_BUFFER_MASK)
+#error TX buffer size TX_BUFFER must be a power of two
+#endif
+
+#ifndef F_CPU
+#error F_CPU not defined, set it in Makefile
+#endif
+
+#define UBRR_VAL ((F_CPU + 8UL * UART_BAUD) / (16UL*UART_BAUD) - 1)
+
+static volatile unsigned char buffer[TX_BUFFER];
+static volatile unsigned char b_head, b_tail, b_overrun;
+/*
+ * b_head == b_tail: empty queue
+ * b_head + 1 == b_tail: full queue
+ * b_overrun is set but not currently handled in any way
+ */
+
+void uart_init()
+{
+ UBRR0H = (unsigned char)(UBRR_VAL >> 8);
+ UBRR0L = (unsigned char)(UBRR_VAL & 0xFF);
+
+ UCSR0C = _BV(USBS0) | _BV(UCSZ00) | _BV(UCSZ01);
+ UCSR0B = _BV(TXEN0); // enable TX only
+
+ b_head = 0;
+ b_tail = 0;
+ b_overrun = 0;
+}
+
+ISR(USART_UDRE_vect) // tx end irq
+{
+ // maybe handle overrun here?
+ if (b_head == b_tail) { // queue empty
+ UCSR0B &= ~_BV(UDRIE0); // disable IRQ
+ } else {
+ UDR0 = buffer[b_tail];
+ b_tail = (b_tail + 1) & TX_BUFFER_MASK;
+ }
+}
+
+// low-level byte sending
+unsigned char uart_tx_byte(unsigned char byte, unsigned char wait)
+{
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+ retry:
+ if (((b_head + 1) & TX_BUFFER_MASK) == b_tail) {
+ if (wait) {
+ NONATOMIC_BLOCK(NONATOMIC_FORCEOFF) {
+ while (((b_head + 1) & TX_BUFFER_MASK)
+ == b_tail)
+ ;
+ }
+ goto retry;
+ }
+
+ b_overrun = 1;
+ return 0;
+ }
+
+ buffer[b_head] = byte;
+ b_head = (b_head + 1) & TX_BUFFER_MASK;
+
+ UCSR0B |= _BV(UDRIE0);
+ }
+ return 1;
+}
+
+// ASCII hex bytes, for debugging purposes
+
+#define hex_nibble(x) ((x) < 10 ? '0' + (x) : 'A' + (x) - 10)
+
+unsigned char uart_tx_hex(unsigned char byte, unsigned char wait)
+{
+ if (
+ uart_tx_byte(hex_nibble(byte >> 4), wait)
+ && uart_tx_byte(hex_nibble(byte & 0xF), wait)
+ )
+ return 1;
+ else
+ return 0;
+}
+
+unsigned char uart_tx_hex2(unsigned short word, unsigned char wait)
+{
+ if (
+ uart_tx_byte(hex_nibble((word >> 12) & 0xF), wait)
+ && uart_tx_byte(hex_nibble((word >> 8) & 0xF), wait)
+ && uart_tx_byte(hex_nibble((word >> 4) & 0xF), wait)
+ && uart_tx_byte(hex_nibble( word & 0xF), wait)
+ )
+ return 1;
+ else
+ return 0;
+}
+
--- /dev/null
+#ifndef UART_H__
+#define UART_H__ 1
+
+void uart_init();
+unsigned char uart_tx_byte(unsigned char byte, unsigned char wait);
+unsigned char uart_tx_hex(unsigned char byte, unsigned char wait);
+unsigned char uart_tx_hex2(unsigned short word, unsigned char wait);
+
+#endif /* !UART_H__ */
+
--- /dev/null
+#!/usr/bin/perl -w
+
+use strict;
+use POSIX qw(strftime);
+
+my $git = `git rev-parse --short HEAD`;
+chomp $git;
+
+my $now = strftime('%Y%m%d', localtime(time));
+
+print <<EOF;
+/* DO NOT EDIT - GENERATED BY $0 */
+
+unsigned char version[] = {
+EOF
+
+print hex2c($now, "date");
+print hex2c($git, "git revision");
+
+print "};\n\nunsigned char version_len = 8;\n";
+print "\n/* EOF - this file has not been truncated */\n\n";
+
+sub hex2c {
+ my ($data, $comment) = @_;
+
+ my $data1 = $data;
+ $data1 .= '0' if (length($data1) & 1 == 1);
+ $data1 =~ s/(..)/0x$1, /g;
+ return "\t$data1 /* $comment $data */\n";
+}
+
https://www.fi.muni.cz/~kas/git / scxreader.git / commitdiff