Need help on NRF24LE1 Auto retransmit & Auto ACK confusions

RE: Need help on NRF24LE1 Auto retransmit & Auto ACK confusions

junma — Thu, 15 Oct 2015 09:04:44 GMT

@Hung Bui Ok, I see. Thank you for all the help!

RE: Need help on NRF24LE1 Auto retransmit & Auto ACK confusions

Hung Bui — Wed, 14 Oct 2015 09:54:27 GMT

@junma: Yes, normally when you just want to broadcast, and don't expect any data transmitting back from the peer you should turn off AutoACK (NO_ACK = 1). It's what I suggested at option 1. But you can use option 2 if you want, but it's not recommended. You won't gain anything but more power consumption.

And yes, if you disable Auto-ack (NOACK=1), Auto-retransmit doesn't work. Please have a look at the block diagram at Figure 12 in nRF24LE1 Spec v1.6

RE: Need help on NRF24LE1 Auto retransmit & Auto ACK confusions

junma — Tue, 13 Oct 2015 03:03:14 GMT

Hi Hung Bui, I was once talked to one NORDIC sales agent, he said if I want to use broadcast way, I shall disable the Auto ACK. And there is another concern, since I introduced the frequency hopping also, I found frequency hopping sometimes will confilict with Auto ACK, I don't know the root cause, but the result are just very instable, and data lost happens often when doing 1 sender to 5 receivers test.

Back to the question, so you mean that if I disable the Auto-ACK, that means the Auto-Retransmit settings are also not work, right?

RE: Need help on NRF24LE1 Auto retransmit & Auto ACK confusions

Hung Bui — Mon, 12 Oct 2015 10:30:47 GMT

Hi Junma,

I assume that you don't plan to send data from your receivers to the sender. You can't disable Auto ACK and still have Auto Retransmit.

There are 2 options for you:

Disable Auto ACK, and send a packet 15 times manually before switch to the new packet.
Enable Auto ACK and set the number of auto retransmit to 15. Since the receiver only receives, it doesn't mater if you enable Auto ACK or not. But you will consume more power because the transmitter will stay in receiving mode for a while waiting for ACK on each packet.