Bringing up 125Kbps Coded PHY on NRF52840

[user3344]

Ive been working on this for some time and can not get two boards successfully communicating using the 125Kbps on the NRF52840.  I am simply having one chip transmit advertising packets, and the other receive them.  It is working for 1Mbps and 2Mbps, but I can not get 125Kbps working.  Im assuming I should just have to change the radio configuration and the rest of the code should work, correct?  I have tried working with the following examples.

https://devzone.nordicsemi.com/f/nordic-q-a/19945/ble-5-transmiter-receiver-examples-nrff52840/77618#77618

https://devzone.nordicsemi.com/f/nordic-q-a/44581/how-do-i-set-bitrate-125kbit-250kbit-or-500kbit-in-nrf5_sdk_15-2-0_9412b96-examples-proprietary_rf-esb_low_power_prx-and-esb_low_power_prx-projects

https://devzone.nordicsemi.com/f/nordic-q-a/22094/rx-on-le-coded-phy

Here is my working code for 1Mbit.  Any chance I could get some help on getting this to work with 125Kbps?

#define PACKET_S1_FIELD_SIZE      (0UL)  /**< Packet S1 field size in bits. */
#define PACKET_S0_FIELD_SIZE      (0UL)  /**< Packet S0 field size in bits. */
#define PACKET_LENGTH_FIELD_SIZE  (0UL)  /**< Packet length field size in bits. */


#define PACKET_BASE_ADDRESS_LENGTH  (4UL)                   //!< Packet base address length field size in bytes
#define PACKET_STATIC_LENGTH        (1UL)                   //!< Packet static length in bytes
#define PACKET_PAYLOAD_MAXSIZE      (PACKET_STATIC_LENGTH)  //!< Packet payload maximum size in bytes
#define CRC_POLYNOMIAL_INIT_SETTINGS  ((0x5B << 0) | (0x06 << 8) | (0x00 << 16))

uint8_t access_address[4] = {0xD6, 0xBE, 0x89, 0x8E};
uint8_t seed[3] = {0x55, 0x55, 0x55};

void radio_configure(uint8_t *p_data)
{
	NRF_RADIO->POWER = RADIO_POWER_POWER_Disabled << RADIO_POWER_POWER_Pos;
	NRF_RADIO->POWER = RADIO_POWER_POWER_Enabled << RADIO_POWER_POWER_Pos;
	NRF_RADIO->FREQUENCY = 2UL;  
	NRF_RADIO->SHORTS = 0;
	NRF_RADIO->TXPOWER   = (RADIO_TXPOWER_TXPOWER_Pos8dBm << RADIO_TXPOWER_TXPOWER_Pos);
	NRF_RADIO->MODE      = (RADIO_MODE_MODE_Ble_1Mbit << RADIO_MODE_MODE_Pos); 

	// Radio address config
	NRF_RADIO->PREFIX0 = access_address[3];
	NRF_RADIO->BASE0   = ( (((uint32_t)access_address[2]) << 24)
						 | (((uint32_t)access_address[1]) << 16)
						 | (((uint32_t)access_address[0]) << 8) );

	NRF_RADIO->RXADDRESSES = 0x01UL;  

	NRF_RADIO->PCNF0 =   (((1UL) << RADIO_PCNF0_S0LEN_Pos) & RADIO_PCNF0_S0LEN_Msk)
						 | (((2UL) << RADIO_PCNF0_S1LEN_Pos) & RADIO_PCNF0_S1LEN_Msk)
						 | (((6UL) << RADIO_PCNF0_LFLEN_Pos) & RADIO_PCNF0_LFLEN_Msk);

	NRF_RADIO->PCNF1 =   (((RADIO_PCNF1_ENDIAN_Little)        << RADIO_PCNF1_ENDIAN_Pos) & RADIO_PCNF1_ENDIAN_Msk)
						 | (((3UL)                              << RADIO_PCNF1_BALEN_Pos)  & RADIO_PCNF1_BALEN_Msk)
						 | (((0UL)                              << RADIO_PCNF1_STATLEN_Pos)& RADIO_PCNF1_STATLEN_Msk)
						 | ((((uint32_t)37)  << RADIO_PCNF1_MAXLEN_Pos) & RADIO_PCNF1_MAXLEN_Msk)
						 | ((RADIO_PCNF1_WHITEEN_Enabled << RADIO_PCNF1_WHITEEN_Pos) & RADIO_PCNF1_WHITEEN_Msk);

	NRF_RADIO->TIFS = 150; 
	
	// CRC Config

	NRF_RADIO->CRCPOLY = (uint32_t)CRC_POLYNOMIAL_INIT_SETTINGS;
	NRF_RADIO->CRCCNF = (((RADIO_CRCCNF_SKIPADDR_Skip) << RADIO_CRCCNF_SKIPADDR_Pos) & RADIO_CRCCNF_SKIPADDR_Msk)
						| (((RADIO_CRCCNF_LEN_Three)      << RADIO_CRCCNF_LEN_Pos)       & RADIO_CRCCNF_LEN_Msk);
						
	NRF_RADIO->CRCINIT = ((uint32_t)seed[0]) | ((uint32_t)seed[1])<<8 | ((uint32_t)seed[2])<<16;

	//match ID code
	NRF_RADIO->DAB[0]=  0;
	NRF_RADIO->DAP[0]=  0;
	NRF_RADIO->DACNF = 	0;

	//first packet in buffer
	NRF_RADIO->PACKETPTR = (uint32_t)&(p_data[0]);

	//radio should be configured at this point.  Power it up. 
	NRF_RADIO->EVENTS_READY = 0U; //clear the read flad
	
	// Enable radio and wait for ready
	NRF_RADIO->TASKS_RXEN = 1U;
	while (NRF_RADIO->EVENTS_READY == 0U)
	{
		// wait
	}
	
	NRF_RADIO->EVENTS_END = 0U; //radio ready, clear flag

	//ready! run this next line from main
	//NVIC_EnableIRQ(RADIO_IRQn);
	//NRF_RADIO->TASKS_START = 1U; // Start listening and wait for address received event
}

[catsunami]

Take a look at the dtm example in the SDK (15.3.0), it sets up a connection using 125K or 500K. However, the thing I think you're missing is the PCNF0_PLEN_LongRange setting.

[user3344]

That was the problem.  In case anyone else finds this thread, here is a working solution for the nrf52840

#define DTM_PAYLOAD_MAX_SIZE 255
void radio_configure_coded_phy()
{
	uint32_t          m_address           = 0x71764129;
	uint8_t           m_crcConfSkipAddr   = 1;
    uint8_t           m_crcLength         = RADIO_CRCCNF_LEN_Three;       /**< CRC Length (in bytes). */
	uint8_t           m_packetHeaderLFlen = 8;                            /**< Length of length field in packet Header (in bits). */
	uint8_t           m_packetHeaderS0len = 1;                            /**< Length of S0 field in packet Header (in bytes). */
	uint8_t           m_packetHeaderS1len = 0;  
	uint8_t           m_packetHeaderPlen  = RADIO_PCNF0_PLEN_8bit;        /**< Length of the preamble. */
	uint8_t           m_static_length     = 0;                            /**< Number of bytes sent in addition to the var.length payload. */
	uint32_t          m_balen             = 3;                            /**< Base address length in bytes. */
	uint32_t          m_endian            = RADIO_PCNF1_ENDIAN_Little;    /**< On air endianess of packet, this applies to the S0, LENGTH, S1 and the PAYLOAD fields. */
	uint32_t          m_whitening         = RADIO_PCNF1_WHITEEN_Disabled; /**< Whitening disabled. */
	uint32_t          m_crc_poly          = 0x0000065B;                   /**< CRC polynomial. */
	uint32_t          m_crc_init          = 0x00555555;   
	
	//reset radio
	NRF_RADIO->SHORTS          = 0;
	NRF_RADIO->EVENTS_DISABLED = 0;
	NRF_RADIO->TASKS_DISABLE   = 1;

	while (NRF_RADIO->EVENTS_DISABLED == 0)
	{
			// Do nothing
	}

	NRF_RADIO->EVENTS_DISABLED = 0;
	NRF_RADIO->TASKS_RXEN      = 0;
	NRF_RADIO->TASKS_TXEN      = 0;
	
	//prepare
	NRF_RADIO->CRCPOLY      = m_crc_poly;
    NRF_RADIO->CRCINIT      = m_crc_init;
    NRF_RADIO->FREQUENCY    = 2;
    NRF_RADIO->EVENTS_READY = 0;
    NRF_RADIO->SHORTS       = 0;


	NRF_RADIO->TXPOWER = (RADIO_TXPOWER_TXPOWER_Pos8dBm << RADIO_TXPOWER_TXPOWER_Pos);
    NRF_RADIO->MODE    = (RADIO_MODE_MODE_Ble_LR125Kbit << RADIO_MODE_MODE_Pos); //eric

	// Set the access address, address0/prefix0 used for both Rx and Tx address
	NRF_RADIO->PREFIX0    &= ~RADIO_PREFIX0_AP0_Msk;
	NRF_RADIO->PREFIX0    |= (m_address >> 24) & RADIO_PREFIX0_AP0_Msk;
	NRF_RADIO->BASE0       = m_address << 8;
	NRF_RADIO->RXADDRESSES = RADIO_RXADDRESSES_ADDR0_Enabled << RADIO_RXADDRESSES_ADDR0_Pos;
	NRF_RADIO->TXADDRESS   = (0x00 << RADIO_TXADDRESS_TXADDRESS_Pos) & RADIO_TXADDRESS_TXADDRESS_Msk;

	// Configure CRC calculation
	NRF_RADIO->CRCCNF = (m_crcConfSkipAddr << RADIO_CRCCNF_SKIP_ADDR_Pos) |
											(m_crcLength << RADIO_CRCCNF_LEN_Pos);

	// Coded PHY (Long range)
	NRF_RADIO->PCNF0 = (m_packetHeaderS1len << RADIO_PCNF0_S1LEN_Pos) |
								 (m_packetHeaderS0len << RADIO_PCNF0_S0LEN_Pos) |
								 (m_packetHeaderLFlen << RADIO_PCNF0_LFLEN_Pos) |
								 (3 << RADIO_PCNF0_TERMLEN_Pos) |
								 (2 << RADIO_PCNF0_CILEN_Pos) |
								 (RADIO_PCNF0_PLEN_LongRange << RADIO_PCNF0_PLEN_Pos);


	NRF_RADIO->PCNF1 = (m_whitening          << RADIO_PCNF1_WHITEEN_Pos) |
										 (m_endian             << RADIO_PCNF1_ENDIAN_Pos)  |
										 (m_balen              << RADIO_PCNF1_BALEN_Pos)   |
										 (m_static_length      << RADIO_PCNF1_STATLEN_Pos) |
										 (DTM_PAYLOAD_MAX_SIZE << RADIO_PCNF1_MAXLEN_Pos);

	
		//first packet in buffer
		NRF_RADIO->PACKETPTR = (uint32_t)&RADIO_RX_BUFFER[advpktbufferptr];

		NRF_RADIO->SHORTS = (RADIO_SHORTS_READY_START_Enabled << RADIO_SHORTS_READY_START_Pos)|
												(RADIO_SHORTS_ADDRESS_RSSISTART_Enabled << RADIO_SHORTS_ADDRESS_RSSISTART_Pos);
	
	  //radio should be configured at this point.  Power it up. 
		NRF_RADIO->EVENTS_READY = 0U; //clear the read flad
    // Enable radio and wait for ready
    NRF_RADIO->TASKS_RXEN = 1U;
    while (NRF_RADIO->EVENTS_READY == 0U)
    {
        // wait
    }
    NRF_RADIO->EVENTS_END = 0U; //radio ready, clear flag
    NRF_RADIO->INTENSET=0x00000008; //on event end
	
		//ready! run this next line from main
		NVIC_EnableIRQ(RADIO_IRQn);

    NRF_RADIO->TASKS_START = 1U; // Start listening and wait for address received event
}