ESB communication between nRF24L01 and nRF51

[nordicdev]

HI, I have a remote control with nRF24L01. It was talking with Gen1(uses nRF24L01) product via ESB. Now, I am developing Gen2 product*using nRF51822xxaa) and I need to support backwards compatibility with the remote control, in other words, I need to make nRF51 to talk with nRF24L01 via ESB. I am able to receive from nRF24L01. But, only when I turn the CRC off. If I make CRC to be the same as nRF24L01(which is 16bit CRC), I am not receiving anything from the remote control. Please help.

This is the init settings for nRF24L01:

hash define RF_CHANNEL  	40 //physical channel frequency MHz (2400+RF_CHANNEL)

hash define RF_POWER_DB		3	//0:-18dBm, 1:- 12dBm, 2:-6dBm, 3:0dBm

hash define RF_ADDR_WIDTH	4 //the address is 4 bytes

hash define RF_RETRANSMITS	6	//auto retransmit

hash define RF_RETRANS_DELAY 750	//wait for the ACK (us)

hash  define BROADCAST_ADDR_BYTE1	0x7E

hash define BROADCAST_ADDR_BYTE2	0x7E

hash define BROADCAST_ADDR_BYTE3	0x7E

hash define BROADCAST_ADDR_BYTE4	0x6E

	// Enable the radio clock
	RFCKEN = 1;

	//close all pipes
	hal_nrf_close_pipe(HAL_NRF_ALL);
addr[RF_ADDR_WIDTH] = {BROADCAST_ADDR_BYTE1, BROADCAST_ADDR_BYTE2, BROADCAST_ADDR_BYTE3, BROADCAST_ADDR_BYTE4};

	hal_nrf_set_address(HAL_NRF_TX, addr); 

	hal_nrf_set_address(HAL_NRF_PIPE0, addr); 

	// Set rf channel 2430
	hal_nrf_set_rf_channel(RF_CHANNEL);
	
	// Set the RF_SETUP register
	hal_nrf_set_output_power(RF_POWER_DB); 
	//hal_nrf_set_datarate(HAL_NRF_1MBPS); //1Mbps data rate 	
	hal_nrf_set_datarate(HAL_NRF_250KBPS);

	// Set CRC16
	hal_nrf_set_crc_mode(HAL_NRF_CRC_16BIT); 	
	
	// Set address width
	hal_nrf_set_address_width(RF_ADDR_WIDTH); 

	// Set auto retries(ARC) and delay(ARD, us)
	hal_nrf_set_auto_retr(RF_RETRANSMITS, RF_RETRANS_DELAY);

	// Enable payload with ack and Dynamic payload length
	hal_nrf_activate_features(); //this chip does not need activate, so the func is empty
	hal_nrf_enable_ack_payload(true);
	hal_nrf_enable_dynamic_payload(true);	 //dynamic payload length
	
	// Enable Pipe0 Dynamic payload length 
	hal_nrf_setup_dynamic_payload(0x01);

	// Enable pipe0 with auto ack
	hal_nrf_open_pipe(HAL_NRF_PIPE0, true);

	// Set rx payload width to the number of bytes expected
	hal_nrf_set_rx_payload_width(HAL_NRF_PIPE0, RF_PAYLOAD_LENGTH);
	
	// Flush tx and rx fifo
	hal_nrf_flush_rx();
	hal_nrf_flush_tx();	 	
	
	
	// Configure radio as PTX  
	hal_nrf_set_operation_mode(HAL_NRF_PTX);

	// Power up radio
	hal_nrf_set_power_mode(HAL_NRF_PWR_UP);

	ptx_check_ack.enable = false;


**This is the init settings for nRF51822xxaa:**

    (void)nrf_esb_init(NRF_ESB_MODE_PRX);
		
nrf_esb_set_crc_length(NRF_ESB_CRC_LENGTH_2_BYTE);

nrf_esb_set_datarate(NRF_ESB_DATARATE_250_KBPS);

nrf_esb_set_retransmit_delay(2750);

nrf_esb_set_base_address_length(NRF_ESB_BASE_ADDRESS_LENGTH_4B);

nrf_esb_set_address_prefix_byte(0, 0x7e);

nrf_esb_set_base_address_0(0x006e7e7e);

 nrf_esb_set_channel(40);

    // Load data into TX queue
 my_tx_payload[0] = 0xEF;

    (void)nrf_esb_add_packet_to_tx_fifo(PIPE_NUMBER, my_tx_payload, TX_PAYLOAD_LENGTH, NRF_ESB_PACKET_USE_ACK);

    (void)nrf_esb_add_packet_to_tx_fifo(PIPE_NUMBER, my_tx_payload, TX_PAYLOAD_LENGTH, NRF_ESB_PACKET_USE_ACK);

    (void)nrf_esb_add_packet_to_tx_fifo(PIPE_NUMBER, my_tx_payload, TX_PAYLOAD_LENGTH, NRF_ESB_PACKET_USE_ACK);

    
    // Enable ESB to start receiving
    (void)nrf_esb_enable();

[Jørgen Kvalvaag]

A few comments:

1. Are you setting the correct addresses on both sides? Your example code uses 0x006e7e7e on nRF51 and 0x7e7e7e6e on nRF24L01. Also, the first byte of the address must avoid certain values, like 0xAA and 0x55, perhaps also 0x00 but I don't remember for sure. But then again you wouldn't receive any data with crc off...

2. With CRC off did you check that you receive actual valid data? Without any CRC checking there is quite high probability that random noise could be interpreted as data by the radio.

3. It looks like you are using ESB from SDK release 10 or lower. nRF5 SDK 11.0.0 contains a new ESB implementation, so if you are just starting on this project I would suggest upgrading your SDK.

[nordicdev]

Thanks for the reply. I have solved the issue. It is : nrf_esb_set_base_address_length(NRF_ESB_BASE_ADDRESS_LENGTH_3B); and not 4B. This is because, the base addr 0 has only 3 valid bytes: nrf_esb_set_base_address_0(0x006e7e7e);