TMP127Q1.cpp

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// Copyright (c) 2024 anabrid GmbH
// Contact: https://www.anabrid.com/licensing/
//
// SPDX-License-Identifier: MIT OR GPL-2.0-or-later
 
#include "TMP127Q1.h"
 
const SPISettings functions::TMP127Q1::DEFAULT_SPI_SETTINGS{4'000'000, MSBFIRST, SPI_MODE0};
 
float functions::TMP127Q1::read_temperature() const {
  auto raw = transfer16(0);
  return raw_to_float(raw);
}
 
float functions::TMP127Q1::raw_to_float(uint16_t raw) {
  auto signed_raw = raw_to_signed_raw(raw);
  return static_cast<float>(signed_raw) * 0.03125f;
}
 
int16_t functions::TMP127Q1::raw_to_signed_raw(uint16_t a) {
  // Convert to signed integer and use arithmetic right-shift, which keeps sign bit.
  // Last two bits are always 1 and need to be shifted out to result in 14bit value.
  uint16_t b = (a >> 2);
  // However, for proper two complement after the shift we need to add the two 1
  // again from the left.
  if (a >= 0xC000)
    b |= 0xC000;
  int16_t c = (int16_t)b;
  return c;
}
 
functions::TMP127Q1::TMP127Q1(bus::addr_t address, uint8_t alt_function_idx)
    : DataFunction(address, alt_function_idx, DEFAULT_SPI_SETTINGS) {}