1 files changed, 117 insertions, 0 deletions
diff --git a/minion/src/temperature.cpp b/minion/src/temperature.cpp
new file mode 100644
index 0000000..1231e24
--- /dev/null
+++ b/minion/src/temperature.cpp
@@ -0,0 +1,117 @@
+#include "temperature.hpp"
+
+#include <Arduino.h>
+
+TemperatureSensor::TemperatureSensor(uint8_t pin) noexcept : _pin(pin)
+{
+	pinMode(_pin, OUTPUT);
+}
+
+auto TemperatureSensor::read_temperature() noexcept -> TemperatureSensorStatus
+{
+	// Send start signal and wait
+	digitalWrite(_pin, LOW);
+	delay(TemperatureSensorTiming::START_SIGNAL_TIME_MILLIS);
+
+	// Pull up and wait for response
+	digitalWrite(_pin, HIGH);
+	delayMicroseconds(TemperatureSensorTiming::RESPONSE_SIGNAL_WAIT_TIME_MICROS);
+
+	pinMode(_pin, INPUT);
+
+	// The sensor sends a LOW signal and keeps it for 80us
+	if (!_wait_read(LOW, TemperatureSensorTiming::RESPONSE_SIGNAL_TIME_MICROS))
+	{
+		return TemperatureSensorStatus::TIMEOUT;
+	}
+
+	// The sensor sends a HIGH signal and keeps it for 80us
+	if (!_wait_read(HIGH, TemperatureSensorTiming::RESPONSE_SIGNAL_TIME_MICROS))
+	{
+		return TemperatureSensorStatus::TIMEOUT;
+	}
+
+	uint8_t data_bytes[TEMPERATURE_SENSOR_RESPONSE_DATA_BYTE_CNT] = { 0U,
+																	  0U,
+																	  0U,
+																	  0U,
+																	  0U };
+
+	uint8_t bit_index = BITS_IN_BYTE - 1U;
+	uint8_t byte_index = 0U;
+
+	for (uint16_t index = 0U;
+		 index < (BITS_IN_BYTE * TEMPERATURE_SENSOR_RESPONSE_DATA_BYTE_CNT);
+		 index++)
+	{
+		// Wait for the start to transmit signal
+		if (!_wait_read(
+				LOW,
+				TemperatureSensorTiming::START_TO_TRANSMIT_SIGNAL_TIME_MICROS + 5U
+			))
+		{
+			return TemperatureSensorStatus::TIMEOUT;
+		}
+
+		const auto start_time = micros();
+
+		if (!_wait_read(HIGH, TemperatureSensorTiming::DATA_TRANSMIT_TIMEOUT_MICROS))
+		{
+			return TemperatureSensorStatus::TIMEOUT;
+		}
+
+		// A voltage length greater than 40 means the bit is a 1
+		if ((micros() - start_time) > 40U)
+		{
+			data_bytes[byte_index] |= static_cast<uint8_t>(1U << bit_index);
+		}
+
+		// Continue to the next byte if it's the last bit
+		if (bit_index == 0U)
+		{
+			// Restart at the MSB
+			bit_index = BITS_IN_BYTE - 1U;
+
+			byte_index++;
+			continue;
+		}
+
+		bit_index--;
+	}
+
+	// Restore pin to initial state
+	pinMode(_pin, OUTPUT);
+	digitalWrite(_pin, HIGH);
+
+	_temperature = data_bytes[2];
+
+	auto sum = data_bytes[0] + data_bytes[2];
+
+	if (data_bytes[4] != sum)
+	{
+		return TemperatureSensorStatus::CHECKSUM_ERROR;
+	}
+
+	return TemperatureSensorStatus::OK;
+}
+
+auto TemperatureSensor::temperature() const noexcept -> uint8_t
+{
+	return _temperature;
+}
+
+// NOLINTNEXTLINE(bugprone-easily-swappable-parameters)
+auto TemperatureSensor::_wait_read(uint8_t level, size_t timeout_micros) noexcept -> bool
+{
+	const auto start_time = micros();
+
+	while (digitalRead(_pin) == level)
+	{
+		if ((start_time + timeout_micros) < micros())
+		{
+			return false;
+		}
+	}
+
+	return true;
+}