More NRF24L01+ questions on programming

[longpole001]

Hi Guys ,
I am looking at a module NRF24L01+ rf transceiver , which uses interface of SPI .
Since the PIC i am using has no SPI, i have allocated i/o pins to connect it , and using shiftout/ shiftin to get data in/out

this module spec states it requires that the SPI present data , LSBbyte to MSByte , with MSBit in each Byte first
eg command D7 -D0 , LSB databyte d7-d0 , MSB databyte D15-d8

however i am not completely sure what it expects in correct order given the above SPI requirement

example - to configure a RX pipe0 address of 5 bytes ( its expecting 5 bytes) , i would think i would need to do the following in the order 1- 6 shown
Or would i need to process all but the command byte in reverse order given eg 1 , then 6 to 2

i guess the spec sheet has me a bit confused, any input on if i have interpreted this correct ( eg order 1-6) would be good

http://www.nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01


i have written code to do the following

1. send the command byte = write_reg = $20
2. send the register byte = RX_address_p0 = $0A
3. Send byte 1 = "N" = $4E
4. Send byte 2 = "E" = $45
5 Send byte 3 = "T" = $54
6 send byte 4 = "1" = $01
7 send byte 5 = "4"= $04






Rf_Common_setup:

'1. Set Address number of Bytes for all Pipes
data_out[0]= Write_reg ' Command
data_out(1)= Setup_aw ' Setup Address width all pipes
data_out[2]= $03 ' $00: illigal, $01: 3 bytes, $02: 4 bytes,$03: 5bytes
num_byte=2
gosub SPI_write

'2a. ------ Rx Address for Pipe 0 ------
data_out[0]= Write_reg ' Command
data_out(1)= Rx_addr_p0 ' Rx address for pipe0
data_out[2]= $4E ' "N" '5 byte address
data_out[3]= $45 ' "E"
data_out[4]= $54 ' "T"
data_out[5]= $01 ' "1"
data_out[6]= $04 ' "4"
num_byte=6
gosub SPI_write

return


SPI_write:
SPI_X = 0 ' Ensure SPI_X = 0
CSN = 0 ' Chip enable
For SPI_X = 0 to Num_byte ' loop for # byte
Shiftout SI, SCK, MSBFIRST, [data_out(SPI_X)] ' Send write enable command
next SPI_X
CSN = 1 ' Disable to execute command

return

[HenrikOlsson]

Hi,
I've never used this device (yet - I've had a couple of tranceivers for a while but haven't gotten around to playing with them) but overall I'd say you're on the right track. The byte and bit order seems to be correct.

However, if you look at the W_REGISTER command in the datasheet you'll see that it's stated as 001A AAAA where the five A's represents the adress. In your code you seem to have the command and the adress split into to separate bytes.

I think you should do something like:

Data_Out[0] = Write_Reg + Setup_aw ' Set adress width for all pipes
Data_Out[1] = $03 ' $03=5bytes for all pipes
Num_Byte = 1
GOSUB SPI_WRITE

Data_Out[0] = Write_Reg + RX_Adress_P0
Data_Out[1] = "N"
Data_Out[2] = "E"
Data_Out[3] = "T"
Data_Out[4] = "1"
Data_Out[5] = "4"
Num_Byte = 5
GOSUB SPI_Write
But again, that's just MY interpretation of the datasheet.

/Henrik.

[longpole001]

yep i think your correct , also reading more , i found a note saying LSByte of 5 bytes to be written to RX_Addr_p0 is written first , so if i want to give an address of "NET14" . then i would need to reverse the data out order of the example ?

'2a. ------ Rx Address for Pipe 0 ------
data_out[0]= Write_reg ' Command
data_out(1)= Rx_addr_p0 ' Rx address for pipe0
data_out[2]= $4E ' "N" '5 byte address
data_out[3]= $45 ' "E"
data_out[4]= $54 ' "T"
data_out[5]= $01 ' "1"
data_out[6]= $04 ' "4"
num_byte=6
gosub SPI_write