R_RX_PL_WID

Question

Dear DevZone, 
 2 NRF24L01+ involved 
 1 PTX, autoAck, DPL, (FEATURE = 6) but currently payloads are fixed to 10 bytes long for testing. Speaks to Pipe 1, but works nice too with pipe 0 
 1 PRX, with same FEATURE which feeds ack payloads with direct command W_ACK_PAYLOAD currently fixed to 6 bytes long 
 The communication is perfect... as long as I force payload length manually to 10 in order to read RX FIFO. PRX displays perfectly received payloads, and PTX displays nicely the attached ack message. There is no packet lost, no MAX_RT asserted. BUT, when I read R_RX_PAYLOAD with the direct command R_RX_PL_WID in order to use DPL, I get the value 67 which obviously makes me crazy. I run in a loop for 1 week without improvement. 
 Help is welcome. 
 Kind regards 
 Jacques

JacquesBrunet · Answer

Hello All, 
 Sometimes, just writing a problem makes it easier to understand. I just realize that the direct command R_RX_PL_WID, needs a second SPI transmission to grab the result... what I forgot in my routine ! Since command 0b0110000 is followed by a 0b11111111 (NOP), it works like a charm. 
 I wish you a nice day 
 Jacques