Figuring out the device state machine for i2c
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ba2e5b84dc
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34be227b97
23
flake.nix
23
flake.nix
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@ -354,6 +354,29 @@
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];
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};
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packages."x86_64-linux"."i2c_lights_" =
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let
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pkgs = import nixpkgs { system = "x86_64-linux"; };
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avr = pkgs.pkgsCross.avr.buildPackages;
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in packages."x86_64-linux"."i2c_lights" { gcc = "${avr.gcc}/bin/avr-gcc"; cflags = mcu_cflags attiny85; avr = true; };
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packages."x86_64-linux"."i2c_lights" =
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{ gcc, cflags, avr }:
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let
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pkgs = import nixpkgs { system = "x86_64-linux"; };
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in mkProgram {
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pkgs = pkgs;
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gcc = gcc;
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cflags = cflags;
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pname = "i2c_lights";
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psrc = ./i2c-lights;
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inherit avr;
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pbuildInputs = [
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(packages."x86_64-linux"."i2c" { inherit gcc cflags; })
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(packages."x86_64-linux"."dio" { inherit gcc cflags; })
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];
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};
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devShell."x86_64-linux" =
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let
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pkgs = import nixpkgs { system = "x86_64-linux"; };
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@ -0,0 +1,73 @@
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#include <avr/interrupt.h>
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#include <avr/sleep.h>
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#include <dio.h>
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#include <i2c.h>
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typedef enum registers {
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POWER_OFF = 0x00,
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SET_LIGHTS = 0x01,
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} registers_e;
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int main(void) {
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i2c_device_t * i2c = i2c_device_init(
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(dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 4 },
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(dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 3 },
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0x93,
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3
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);
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dio_t blue = (dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 0 };
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dio_t green = (dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 1 };
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dio_t red = (dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 2 };
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dio_set_direction(&blue, LINE_OUT);
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dio_set_direction(&green, LINE_OUT);
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dio_set_direction(&red, LINE_OUT);
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set_sleep_mode(SLEEP_MODE_IDLE);
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while (1) {
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sei();
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sleep_mode();
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cli();
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i2c_device_step(i2c_device_t *i2c);
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// Now, it's necessary to check whether the register has been set
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// /* SDA has changed. If it's low, let's listen for data */
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// if (!dio_read(i2c.sda)) {
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// /* data incoming. Read the address */
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// uint8_t status = i2c_ok;
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// uint8_t addr = i2c_client_read_byte(&i2c, &status);
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// if (addr == 0x93) {
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// /* Send the ack signal by pulling SDA low for one tick */
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// i2c_client_write_bit(&i2c, 0, &status);
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// uint8_t reg = i2c_client_read_byte(&i2c, &status);
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// switch (reg) {
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// case POWER_OFF:
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// /* turn all of the lights off and put the device into lowest sleep mode */
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// break;
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// case SET_LIGHTS:
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// uint8_t light_status = i2c_client_read_byte(&i2c, &status);
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// dio_set(&red, light_status & _BV(2));
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// dio_set(&green, light_status & _BV(1));
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// dio_set(&blue, light_status & _BV(0));
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// break;
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// default:
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// /* unrecognized register */
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// i2c_client_write(&i2c, 1, &status);
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// }
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// } else {
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// /* The message was not for us, so wait until the bus goes idle */
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// bus_state_e state = ACTIVE;
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// while (1) {
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// sei();
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// sleep_mode();
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// cli();
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// }
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// }
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// }
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}
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}
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@ -0,0 +1,147 @@
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i2c_device_t * i2c_device_init(dio_t clock, dio_t data, uint8_t address, uint8_t register_count) {
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i2c_device_t *self = malloc(sizeof(i2c_device_t) + register_count);
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self->sda = data;
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self->scl = clock;
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self->addr = address;
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self->bus_state_e = IDLE;
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self->register_count = register_count;
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self->target_register = -1;
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for (int i = 0; i < register_count; i++) {
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self->registers[i] = 0;
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}
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return self
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}
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/*
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void i2c_device_write_bit(i2c_bus_t *bus, uint8_t value, i2c_error_e *error) {
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if (*error != i2c_ok) return;
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while (read_scl(bus) != 0) {
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if (value) {
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set_sda(bus);
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} else {
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clear_sda(bus);
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}
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}
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}
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void i2c_device_write_byte(i2c_bus_t *bus, uint8_t value, i2c_error_e *error) {
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for (int i = 7; i >= 0; i--) {
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i2c_write_bit(bus, value & _BV(i), error);
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}
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}
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uint8_t i2c_device_read_bit(i2c_bus_t *bus, i2c_error_e *error) {
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if (*error != i2c_ok) return 0;
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while (read_scl(bus) == 0) {
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i2c_delay();
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}
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return read_sda(bus);
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}
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uint8_t i2c_device_read_byte(i2c_bus_t *bus, i2c_error_e *error) {
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if (*error != i2c_ok) return 0;
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uint8_t value = 0;
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for (int i = 0; i < 8; i++) {
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value = (value << 1) | i2c_device_read_bit(bus, error);
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}
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return value;
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}
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void i2c_status_to_string(i2c_error_e status, char msg[20]) {
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switch (status) {
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case i2c_ok:
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snprintf(msg, 20, "ok");
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break;
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case i2c_arbitration_lost:
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snprintf(msg, 20, "arbitration lost");
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break;
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case i2c_timeout:
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snprintf(msg, 20, "timeout");
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break;
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case i2c_nak:
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snprintf(msg, 20, "nak");
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break;
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}
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}
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void i2c_wait_for_idle(i2c_device_t *bus, i2c_error_e *error) {
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switch (bus_state) {
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case ACTIVE:
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if (dio_read(&i2c.scl) && !dio_read(&i2c.sda)) {
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state = INACTIVE_1;
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}
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break;
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case INACTIVE_1:
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if (dio_read(&i2c.scl) && dio_read(&i2c.sda)) {
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state = IDLE;
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} else {
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state = ACTIVE;
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}
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break;
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case IDLE:
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break;
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}
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}
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bool i2c_is_idle(i2c_device_t *bus) {
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return bus->state == IDLE,
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}
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*/
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void i2c_device_step(i2c_device_t *self) {
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uint8_t sda = dio_read(self.sda);
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uint8_t scl = dio_read(self.scl);
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i2c_error_e status = i2c_ok;
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switch (self->state) {
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case IDLE:
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if (!sda) self->state = START_SDA;
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break;
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case START_SDA:
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if (sda) {
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self->state = IDLE;
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break;
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}
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if (!scl) self->state = START;
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break;
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case START:
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uint8_t header = i2c_device_read_byte(self, &status);
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uint8_t addr = header >> 1;
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uint8_t mode = header & 0x01;
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if addr == self->addr {
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self->state = ACTIVE_LISTEN;
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if (mode) {
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self->direction = DEVICE_TO_HOST;
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} else {
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self->direction = HOST_TO_DEVICE;
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}
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i2c_device_write_bit(self, 0, &status);
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} else {
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self->state = ACTIVE_IGNORE;
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}
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break;
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case ACTIVE_LISTEN:
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// Do all of the stuff to read data from the host
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break;
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case ACTIVE_IGNORE:
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break;
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case INACTIVE:
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break;
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}
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}
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/*
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void i2c_device_release_clock(i2c_device_bus_t *bus) {
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dio_set(bus->scl);
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}
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*/
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31
i2c/i2c.c
31
i2c/i2c.c
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@ -209,34 +209,3 @@ uint8_t i2c_read_byte(i2c_bus_t *bus, bool final_nak, i2c_error_e *error) {
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return value;
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}
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/*
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void i2c_host_write(i2c_bus_t *bus, uint8_t address, uint8_t *data, size_t length, i2c_error_e *error) {
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if (*error != i2c_ok) return;
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i2c_host_write_packet(bus, address << 1, error);
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if (*error != ok) return;
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for (int i = 0; i < length; i++) {
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i2c_host_write_packet(bus, data[i], error);
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if (*error != ok) return;
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}
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}
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*/
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void i2c_status_to_string(i2c_error_e status, char msg[20]) {
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switch (status) {
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case i2c_ok:
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snprintf(msg, 20, "ok");
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break;
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case i2c_arbitration_lost:
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snprintf(msg, 20, "arbitration lost");
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break;
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case i2c_timeout:
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snprintf(msg, 20, "timeout");
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break;
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case i2c_nak:
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snprintf(msg, 20, "nak");
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break;
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}
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}
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44
i2c/i2c.h
44
i2c/i2c.h
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@ -15,6 +15,20 @@ You should have received a copy of the GNU General Public License along with thi
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#include <dio.h>
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typedef enum i2c_bus_state {
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IDLE,
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START_SDA,
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START,
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ACTIVE_LISTEN,
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ACTIVE_IGNORE,
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INACTIVE,
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} i2c_bus_state_e;
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typedef enum message_direction {
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HOST_TO_DEVICE,
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DEVICE_TO_HOST,
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} message_direction_e;
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typedef enum {
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i2c_ok,
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i2c_arbitration_lost,
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@ -30,15 +44,19 @@ typedef struct {
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dio_t scl;
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} i2c_bus_t;
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/*
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typedef struct {
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dio_t sda;
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dio_t scl;
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uint8_t addr;
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} i2c_client_t;
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*/
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i2c_bus_state_e state;
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message_direction_e direction;
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i2c_bus_t * i2c_init(dio_t, dio_t);
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uint8_t register_count;
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int8_t target_register;
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uint8_t registers[];
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} i2c_device_t;
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i2c_bus_t * i2c_init(dio_t clock, dio_t data);
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void i2c_start(i2c_bus_t *bus, i2c_error_e *error);
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void i2c_end(i2c_bus_t *bus, i2c_error_e *error);
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@ -51,4 +69,22 @@ uint8_t i2c_read_byte(i2c_bus_t *bus, bool final_nak, i2c_error_e *error);
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void i2c_status_to_string(i2c_error_e status, char msg[20]);
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i2c_device_t * i2c_device_init(dio_t clock, dio_t data, uint8_t address, uint8_t register_count);
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void i2c_device_step(i2c_device_t *);
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void i2c_device_release_bus(i2c_device_t *);
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/*
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void i2c_device_bus_state_update(i2c_device_bus_t *bus);
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void i2c_set_register(i2c_registers_t *regs, i2c_error_e *error) {
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}
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void i2c_register_write(i2c_registers_t *regs, i2c_error_e *error) {
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}
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void i2c_register_read(i2c_registers_t *regs, i2c_error_e *error) {
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}
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*/
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#endif
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@ -0,0 +1,18 @@
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#include <dio.h>
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#include <i2c.h>
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typedef enum registers {
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POWER_OFF = 0x00,
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SET_LIGHTS = 0x01,
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} registers_e;
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int main(void) {
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i2c_bus_t *bus = i2c_init(
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(dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 4 },
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(dio_t){ .ddr = &DDRB, .port = &PORTB, .addr = 3 },
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);
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while(1) {
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}
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}
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