Shortest preamble of a packet, nRF51 can receive.

[Chinook]

What is a minimal length of preamble, such that nRF51 is able to safely receive a packet with? Can it be made (via some magic registers) to be as small as 4 bits? Then it would be possible to implement software support for classic Bluetooth on nRF51 chip. Of course all that pretty hardware for packet encoding/decoding etc would be useless, but anyway it would be a nice possibility.

[Håkon Alseth]

Preamble must be 8 bits. The hardware is not able to run classic bluetooth, as the data rate, on-air modulation, and many other factors is a mismatch.

Cheers, Håkon

[Chinook]

Preamble aside the hardware is able to run classic Bluetooth. Nordic 1Mbps mode satisfies requirements of Bluetooth BR in data rate and on-air modulation quite well. I actually succeeded in establishing connection with a classic Bluetooth device which happened to send a long preamble.