#define PACKET_BASE_ADDRESS_LENGTH  (2UL)  //Packet base address length field size in bytes
#define toggle_mask 1<<7 //this is for the scope

static uint8_t packet = 12; //declare a buffer for our packet to use with easydma

void wait_for_end(){
  while(!(NRF_RADIO->EVENTS_END)){}
  NRF_RADIO->EVENTS_END = 0; //clear end event  
}
void wait_for_ready(){
  while(!(NRF_RADIO->EVENTS_READY)){} 
  NRF_RADIO->EVENTS_READY = 0; //clear ready event
}
void disable_radio(){
  NRF_RADIO->EVENTS_DISABLED = 0; //clear disabled event
  NRF_RADIO->TASKS_DISABLE = 1;
  while(!(NRF_RADIO->EVENTS_DISABLED)){} 
}

void send_token(){
  NRF_GPIO->OUTSET = toggle_mask; //set toggle pin high  
  NRF_RADIO->EVENTS_READY = 0; //clear ready event
  NRF_RADIO->TASKS_TXEN=1; //trigger tx enable task
  delayMicroseconds(15);
  //wait_for_ready(); //since we're switching, maybe we can get around this?
  NRF_RADIO->TASKS_START=1;  //start
  wait_for_end();
  NRF_GPIO->OUTCLR = toggle_mask; //set toggle pin low

  //put radio in RX mode
  NRF_RADIO->EVENTS_READY = 0; //clear ready event
  NRF_RADIO->TASKS_RXEN=1; //trigger rx enable task
  wait_for_ready();  
  NRF_RADIO->TASKS_START=1;
}

void setup() {
  //helpful bitmasks in nrf52_bitfields.h
  //Serial.begin(115200);  //for debug only
  NRF_GPIO->DIRSET = toggle_mask; //set toggling pin to output

  NRF_RADIO->POWER = RADIO_POWER_POWER_Disabled; //turn off radio to reset registers
  delay(10);
  NRF_RADIO->POWER = RADIO_POWER_POWER_Enabled; //turn on radio
  delay(10);

  // Radio config
  NRF_RADIO->TXPOWER   = (RADIO_TXPOWER_TXPOWER_Pos3dBm << RADIO_TXPOWER_TXPOWER_Pos);
  NRF_RADIO->FREQUENCY = 7UL;  // Frequency bin 7, 2407MHz
  NRF_RADIO->MODE      = (RADIO_MODE_MODE_Nrf_2Mbit << RADIO_MODE_MODE_Pos);

  NRF_RADIO->PREFIX0 = ((uint32_t)0xC0 << 0); // Prefix byte of address 0
  NRF_RADIO->BASE0 = 0x01234567UL;  // Base address for prefix 0
  NRF_RADIO->TXADDRESS   = 0x00UL;  // Set device address 0 to use when transmitting
  NRF_RADIO->RXADDRESSES = 0x01UL;  // Enable device address 0 to use to select which addresses to receive

  // Packet configuration
  NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S1LEN_Pos) | (0 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos); 
  NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled << RADIO_PCNF1_WHITEEN_Pos) |
                     (RADIO_PCNF1_ENDIAN_Big       << RADIO_PCNF1_ENDIAN_Pos)  |
                     (2 << RADIO_PCNF1_BALEN_Pos);

  // CRC Config
  NRF_RADIO->CRCCNF = (RADIO_CRCCNF_LEN_Disabled << RADIO_CRCCNF_LEN_Pos); // Number of checksum bits
  //NRF_RADIO->CRCINIT = 0xFFFFUL;   // Initial value
  //NRF_RADIO->CRCPOLY = 0x11021UL;  // CRC poly: x^16 + x^12^x^5 + 1

  NRF_RADIO->MODECNF0 |= RADIO_MODECNF0_RU_Fast << RADIO_MODECNF0_RU_Pos; //turn on fast ramp up
  NRF_RADIO->SHORTS = 0; //turn off all shortcuts, for debug
    
  //packet
  NRF_RADIO->PACKETPTR = (uint32_t)&packet; //set pointer to packet buffer

  //start HFCLK
  NRF_CLOCK->TASKS_HFCLKSTART = 1;
  while(!(NRF_CLOCK->HFCLKSTAT & CLOCK_HFCLKSTAT_STATE_Msk)){} //wait for hfclk to start
  delay(10);
  
  send_token(); //send a starting token
  while(1){   
    if ( NRF_RADIO->EVENTS_END ){
      NRF_RADIO->EVENTS_END = 0; //clear end event
      packet += 1; //increment for fun
      send_token();
    }
    //delay(100);
    //Serial.println(packet);  //for debug only
  }
}
 
void loop() {}