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nRF24 / RF24

OSI Layer 2 driver for nRF24L01 on Arduino & Raspberry Pi/Linux Devices
https://nrf24.github.io/RF24
GNU General Public License v2.0
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[Question] Get received message Packet Control Field #768

Closed VasilyRakche closed 3 years ago

VasilyRakche commented 3 years ago

Hey,

I was comparing messages received with nRF and with other device. I see that the Packet Control Field is cut-off from the message. Based on the nRF24 Datasheet this field is part of Enhanced ShockBurst, image but is not present in regular one: image

So is there a way to get Packet Control Field content, or if there is a way of just switching to regular ShockBurst protocol?

2bndy5 commented 3 years ago

Only the payload is accessible to the user. All other parts of the packet aren't exposed through some API. You can calculate the CRC yourself...

The difference between Enhanced ShockBurst and regular old ShockBurst is only the use of the auto-ack feature. Nordic semi. has a history of making hardware as backward compatible as possible, that's the only reason auto-ack feature can be turned off.

VasilyRakche commented 3 years ago

Got it, but is there still a chance to get Packet Length, Packet ID, or if the ACK flag was set from Packet Control Field through API? image

2bndy5 commented 3 years ago

Sorry there isn't. You can calculate the packet length based on the radio configuration and payload width. You might be able to estimate the Packet ID from the TX ARC after a transmitting the data (info not available at receiver). The NO_ACK bit is directly controlled by the transmitter (asserted when the payload is written to TX FIFO). The radio as a receiver decodes/disassembles the packet as it is received; it does not actually save any artifact or log info containing the data you seek.

pascallanger commented 3 years ago

@VasilyRakche What you want is simply to configure the NRF in ShockBurst and not Enhanced ShockBurst which is done by disabling dynamic payload and auto ack. You also want to diable CRC so that it does not filter packets on anything else than the address and then the NRF gives you the full payload without modification like shown on your pic (minus CRC): image

VasilyRakche commented 3 years ago

@pascallanger Thanks a lot, that was it! That way it retains everything inside the packet!