radio.c

//
// Created by SQ5RWU on 2016-12-24.
//

#include "radio.h"

uint8_t _spi_sendrecv(const uint16_t data_word) {
  GPIO_ResetBits(GPIOC, radioNSELpin);
  // wait for tx buffer
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI2, data_word);

  // wait for data in rx buffer
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
  GPIO_SetBits(GPIOC, radioNSELpin);
  return (uint8_t) SPI_I2S_ReceiveData(SPI2);
}

inline uint8_t radio_rw_register(const uint8_t register_addr, uint8_t value, uint8_t write){
  return _spi_sendrecv(((write ? register_addr | WR : register_addr) << 8) | value);
}

void radio_set_tx_frequency(const float freq_in_mhz) {
  uint8_t hbsel = (uint8_t) ((freq_in_mhz * (30.0f / SI4032_CLOCK)) >= 480.0f ? 1 : 0);

  uint8_t fb = (uint8_t) ((((uint8_t)((freq_in_mhz * (30.0f / SI4032_CLOCK)) / 10) - 24) - (24 * hbsel)) / (1 + hbsel));
  uint8_t gen_div  =  3;  // constant - not possible to change!
  uint16_t fc = (uint16_t) (((freq_in_mhz / ((SI4032_CLOCK / gen_div) * (hbsel + 1))) - fb - 24) * 64000);
  radio_rw_register(0x75, (uint8_t) (0b01000000 | (fb & 0b11111) | ((hbsel & 0b1) << 5)), 1);
  radio_rw_register(0x76, (uint8_t) (((uint16_t)fc >> 8) & 0xff), 1);
  radio_rw_register(0x77, (uint8_t) ((uint16_t)fc & 0xff), 1);
}

void radio_disable_tx() {
  radio_rw_register(0x07, 0x40, 1);
}

void radio_inhibit_tx() {
  // Sleep mode, but with PLL idle mode enabled, in an attempt to reduce drift on key-up.
  radio_rw_register(0x07, 0x43, 1);
}

void radio_soft_reset() {
  radio_rw_register(0x07, 0x80, 1);
}

void radio_enable_tx() {
  radio_rw_register(0x07, 0x4B, 1); // was 0x48 ???
}

int8_t radio_read_temperature() {
  uint8_t temp;
  // Read ADC Value.
  // Temp (degC) = -64 + ADC Value * 0.5
  temp = radio_rw_register(0x11, 0xff, 0);

  // Convert ADC value to signed temperature value.
  int16_t temp_2 = -64 + ((int16_t)temp * 5) / 10;

  // Trigger ADC to capture another measurement.
  radio_rw_register(0x0f, 0x80, 1);

  // Cast temperature value to int8_t and return.
  return (int8_t)temp_2;
}