matemat/poweriface/firmware/main.c

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#include <inttypes.h>
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#include <stdbool.h>
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#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <can.h>
static bool report_change = false;
static void init() {
// Enable GPIO: PB2, PB3, PB4 output, low; PB5 input, pull-up on
PORTB = (PORTB & ~(_BV(PB2) | _BV(PB3) | _BV(PB4))) | _BV(PB5);
DDRB = (DDRB & ~_BV(PB5)) | (_BV(PB2) | _BV(PB3) | _BV(PB4));
// Initialize CAN interface
can_init(BITRATE_125_KBPS);
// Regular receive/transmit mode
can_set_mode(NORMAL_MODE);
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// Filter for messages addressed to us (RTR on)
can_filter_t us = {
.id = 0x001,
.mask = 0x00f,
.flags = {
.rtr = 1,
.extended = 0,
},
};
can_set_filter(0, &us);
// Filter for public messages (RTR off)
can_filter_t pub = {
.id = 0x00f,
.mask = 0x00f,
.flags = {
.rtr = 0,
.extended = 0,
},
};
can_set_filter(1, &pub);
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// Enable interrupts to start reception
sei();
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}
// UART bit-uart_bang 8 bits on the debug port, LSB first, 1 stop bit, no parity, 9600 baud
void uart_bang(uint8_t data) {
// Start bit: low
PORTB &= ~_BV(PB4);
_delay_us(102);
for (uint8_t i = 0; i < 8; i++) {
// data bit
if (data & (_BV(i))) {
PORTB |= _BV(PB4);
} else {
PORTB &= ~_BV(PB4);
}
_delay_us(102);
}
// Stop bit: high (and stay there after)
PORTB |= _BV(PB4);
_delay_us(102);
}
// Bit-bang pattern (LSB first) out the data line
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uint16_t bang(uint16_t data) {
uint16_t in = 0;
for (uint8_t i = 0; i < 16; i++) {
// Data bit
if (data & 1) {
PORTB |= _BV(PB4);
} else {
PORTB &= ~_BV(PB4);
}
// Clock up
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PORTB |= _BV(PB2);
_delay_us(4);
// Clock down
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PORTB &= ~_BV(PB2);
_delay_us(4);
// Read
if (PINB & _BV(PB5)) {
in |= 1;
}
// Shift
data >>= 1;
in <<= 1;
}
// Clear data
PORTB &= ~_BV(PB4);
return in;
}
// Strobe output
void strobe() {
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// Strobe
PORTB |= _BV(PB3);
_delay_us(4);
PORTB &= ~_BV(PB3);
}
static void send_status() {
// Bit-bang register contents in (also send out zeros, but don't strobe)
uint16_t status = bang(0);
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// Send the current state back out to prevent glitches
bang(status);
if (can_check_free_buffer()) {
can_t msg = {
.id = 0x11,
.flags = {
.rtr = 0,
},
.length = 2,
.data = { (uint8_t) (status >> 8), (uint8_t) status, },
};
can_send_message(&msg);
}
}
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static void fire_relay(uint8_t num) {
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if (num == 0) {
bang(0);
strobe();
} else if (num <= 5) {
uint16_t out = 0x0080 >> (num - 1);
bang(out);
strobe();
}
}
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static void loop() {
// Check for new messages
if (can_check_message()) {
can_t msg = { 0 };
uint8_t status = can_get_message(&msg);
if (status != 0) {
switch (msg.id) {
case 0x11:
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send_status();
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break;
case 0x21:
if (msg.length == 1) {
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// stop (d0 = 0) or fire relay (d0 = 1..5)
fire_relay(msg.data[0]);
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// also send out the current status
send_status();
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}
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break;
case 0x4f:
if (msg.length == 1) {
report_change = msg.data[0] ? true : false;
}
break;
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}
}
}
}
int main() {
init();
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while (1) {
loop();
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}
}