flipperzero-firmware/applications/ibutton/one_wire_gpio.h

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C
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2020-11-16 11:21:58 +00:00
#pragma once
#include "flipper.h"
#include "flipper_v2.h"
#include "one_wire_timings.h"
class OneWireGpio {
private:
GpioPin* gpio;
public:
OneWireGpio(GpioPin* one_wire_gpio);
~OneWireGpio();
bool reset(void);
bool read_bit(void);
uint8_t read(void);
void read_bytes(uint8_t* buf, uint16_t count);
void write_bit(bool value);
void write(uint8_t value);
void start(void);
void stop(void);
};
OneWireGpio::OneWireGpio(GpioPin* one_wire_gpio) {
gpio = one_wire_gpio;
}
OneWireGpio::~OneWireGpio() {
stop();
}
void OneWireGpio::start(void) {
gpio_init(gpio, GpioModeOutputOpenDrain);
}
void OneWireGpio::stop(void) {
gpio_init(gpio, GpioModeAnalog);
}
bool OneWireGpio::reset(void) {
uint8_t r;
uint8_t retries = 125;
// wait until the gpio is high
gpio_write(gpio, true);
do {
if(--retries == 0) return 0;
delay_us(2);
} while(!gpio_read(gpio));
// pre delay
delay_us(OneWireTiming::RESET_DELAY_PRE);
// drive low
gpio_write(gpio, false);
delay_us(OneWireTiming::RESET_DRIVE);
// release
gpio_write(gpio, true);
delay_us(OneWireTiming::RESET_RELEASE);
// read and post delay
r = !gpio_read(gpio);
delay_us(OneWireTiming::RESET_DELAY_POST);
return r;
}
bool OneWireGpio::read_bit(void) {
bool result;
// drive low
gpio_write(gpio, false);
delay_us(OneWireTiming::READ_DRIVE);
// release
gpio_write(gpio, true);
delay_us(OneWireTiming::READ_RELEASE);
// read and post delay
result = gpio_read(gpio);
delay_us(OneWireTiming::READ_DELAY_POST);
return result;
}
void OneWireGpio::write_bit(bool value) {
if(value) {
// drive low
gpio_write(gpio, false);
delay_us(OneWireTiming::WRITE_1_DRIVE);
// release
gpio_write(gpio, true);
delay_us(OneWireTiming::WRITE_1_RELEASE);
} else {
// drive low
gpio_write(gpio, false);
delay_us(OneWireTiming::WRITE_0_DRIVE);
// release
gpio_write(gpio, true);
delay_us(OneWireTiming::WRITE_0_RELEASE);
}
}
uint8_t OneWireGpio::read(void) {
uint8_t result = 0;
for(uint8_t bitMask = 0x01; bitMask; bitMask <<= 1) {
if(read_bit()) {
result |= bitMask;
}
}
return result;
}
void OneWireGpio::read_bytes(uint8_t* buffer, uint16_t count) {
for(uint16_t i = 0; i < count; i++) {
buffer[i] = read();
}
}
void OneWireGpio::write(uint8_t value) {
uint8_t bitMask;
for(bitMask = 0x01; bitMask; bitMask <<= 1) {
write_bit((bitMask & value) ? 1 : 0);
}
}