initial version

.gitignore

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+build

Makefile

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+TARGET     = rc5switch
+TARGET_MCU = attiny24
+
+# ---------------------------------------------------------
+
+BUILD   = build
+
+CC      = avr-gcc
+NM      = avr-nm
+SIZE    = avr-size
+OBJCOPY = avr-objcopy
+OBJDUMP = avr-objdump
+
+override CFLAGS  = -g -Wall -Os -mmcu=$(TARGET_MCU) -Wa,-gstabs,-adhlns=$(BUILD)/$(*D)/$(*F).lst -MMD -MP -MF $(BUILD)/$(*D)/$(*F).d -pipe
+override LDFLAGS = -Wl,-Map=$(BUILD)/$(TARGET).map,--cref
+
+# ---------------------------------------------------------
+
+SRC := $(wildcard *.c)
+
+all: $(addprefix $(BUILD)/$(TARGET), .elf .lss .sym .bin .hex _eeprom.bin _eeprom.hex)
+#	@$(SIZE) -x -C --mcu=$(TARGET_MCU) $<
+
+%.lss: %.elf
+	@$(OBJDUMP) -h -S -C $< > $@
+
+%.sym: %.elf
+	@$(NM) -n $< > $@
+
+%.bin: %.elf
+	@$(OBJCOPY) -j .text -j .data -O binary $< $@
+
+%.hex: %.elf
+	@$(OBJCOPY) -j .text -j .data -O ihex $< $@
+
+%_eeprom.bin: %.elf
+	@$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O binary $< $@ 2> /dev/null
+
+%_eeprom.hex: %.elf
+	@$(OBJCOPY) -j .eeprom --change-section-lma .eeprom=0 -O ihex $< $@ 2> /dev/null
+
+$(BUILD)/$(TARGET).elf: $(patsubst %,$(BUILD)/%,$(SRC:.c=.o))
+	@echo " Linking file:  $@"
+	@$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) > /dev/null
+	@$(SIZE) -x -B $^ $@
+
+$(BUILD)/%.o: %.c $(MAKEFILE_LIST)
+	@echo " Building file: $<"
+	@$(shell mkdir -p $(BUILD)/$(*D))
+	@$(CC) -c $(CFLAGS) $< -o $@
+
+clean:
+	rm -rf $(BUILD)
+
+install: $(BUILD)/$(TARGET).hex $(BUILD)/$(TARGET)_eeprom.hex
+	avrdude -c dragon_isp -P usb -p t24 -U flash:w:$(BUILD)/$(TARGET).hex -U eeprom:w:$(BUILD)/$(TARGET)_eeprom.hex
+
+# no self programming, 2.7V BOD, 8MHz internal RC Osz.
+fuses:
+	avrdude -c dragon_isp -P usb -p t24 -U lfuse:w:0xc2:m -U hfuse:w:0xdd:m -U efuse:w:0xff:m
+
+-include $(shell find $(BUILD) -name *.d 2> /dev/null)

main.c

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+/***************************************************************************
+ *   Copyright (C) 04/2011 by Olaf Rempel                                  *
+ *   razzor@kopf-tisch.de                                                  *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; version 2 of the License,               *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/eeprom.h>
+#include <avr/sleep.h>
+
+/*
+ * attiny24: (no self programming, 2.7V BOD, 8MHz internal RC Osz)
+ * LFUSE = 0xC2
+ * HFUSE = 0xDD
+ * EFUSE = 0xFF
+ *
+ * RC5 Input on PB2 (INT0)
+ * PROGMODE Jumper (active low) on PB1
+ * OUTPUT (active low) on PB0
+ */
+
+/* RC5 bitlength is 1778us +/-10% convert to time0 ticks (8us) */
+#define BITWIDTH                (1778 / 8)
+#define BITWIDTH_MIN            (BITWIDTH - (BITWIDTH / 10))
+#define BITWIDTH_MAX            (BITWIDTH + (BITWIDTH / 10))
+
+#define RC5_BITCNT              14
+#define RC5_CMD_MASK            0x37FF
+#define RC5_COMPLETE            0x8000
+
+#define PROGMODE_CHECK()        (!(PINB & (1<<PINB1)))
+#define OUTPUT_ON()             { PORTA &= ~(1<<PORTA0); }
+#define OUTPUT_OFF()            { PORTA |= (1<<PORTA0); }
+
+struct ee_param {
+        uint16_t rc5cmd;
+        uint8_t state;
+};
+
+struct ee_param params;
+struct ee_param params_in_eeprom EEMEM = {
+        .rc5cmd = 0x350C,
+        .state = 0x00,
+};
+
+static uint8_t bitcnt;
+static volatile uint16_t value;
+
+ISR(EXT_INT0_vect)
+{
+        if (bitcnt == 0)
+                value = 0;
+
+        bitcnt++;
+
+        value = (value << 1);
+        if (!(PINB & (1<<PINB2)))
+                value |= 0x0001;
+
+        /* setup sample window for next edge */
+        OCR0A = TCNT0 + BITWIDTH_MIN;
+        OCR0B = TCNT0 + BITWIDTH_MAX;
+
+        /* clear and enable COMPA / COMPB */
+        TIFR0 = (1<<OCF0A) | (1<<OCF0B);
+        TIMSK0 |= (1<<OCIE0A) | (1<<OCIE0B);
+
+        /* disable INT0 until COMPA hits */
+        GIMSK &= ~(1<<INT0);
+}
+
+ISR(TIM0_COMPA_vect)
+{
+        /* clear and enable INT0 */
+        GIFR = (1<<INTF0);
+        GIMSK |= (1<<INT0);
+}
+
+ISR(TIM0_COMPB_vect)
+{
+        /* disable sample window */
+        TIMSK0 &= ~((1<<OCIE0A) | (1<<OCIE0B));
+
+        /* final bit received? */
+        if (bitcnt >= RC5_BITCNT)
+                value |= RC5_COMPLETE;
+
+        bitcnt = 0;
+}
+
+int main(int argc, char *argv[])
+{
+        /* pullup on RC5IN and PROGMEM, OUTPUT is low active */
+        PORTB = (1<<PORTB2) | (1<<PORTB1) | (1<<PORTB0);
+
+        /* INT0: both edges generate interrupt */
+        MCUCR = (1<<ISC00);
+        GIMSK = (1<<INT0);
+
+        /* Timer0: 8Mhz/64 */
+        TCCR0B = (1<<CS01) | (1<<CS00);
+
+        /* load configuration, restore state */
+        eeprom_read_block(&params, &params_in_eeprom, sizeof(struct ee_param));
+        if (params.state) {
+                OUTPUT_ON();
+        } else {
+                OUTPUT_OFF();
+        }
+
+        /* all interrupts can wake up */
+        set_sleep_mode(SLEEP_MODE_IDLE);
+        sei();
+
+        uint16_t old_value = 0x0000;
+
+        while (1) {
+                /* wait for next interrupt */
+                sleep_mode();
+
+                if (value & RC5_COMPLETE) {
+                        /* PROGMODE jumper set? */
+                        if (PROGMODE_CHECK()) {
+                                params.rc5cmd = (value & RC5_CMD_MASK);
+                                eeprom_write_block(&params, &params_in_eeprom, sizeof(struct ee_param));
+
+                        /* current command matches stored one */
+                        } else if (params.rc5cmd == (value & RC5_CMD_MASK) && value != old_value) {
+                                if (params.state) {
+                                        params.state = 0;
+                                        OUTPUT_OFF();
+                                } else {
+                                        params.state = 1;
+                                        OUTPUT_ON();
+                                }
+
+                                eeprom_write_block(&params, &params_in_eeprom, sizeof(struct ee_param));
+                                old_value = value;
+                        }
+
+                        value = 0x0000;
+                }
+        }
+
+        return 0;
+}