nRF24L01+ Address byte order

[Carlos Cuevas]

Hello, I would like to know if the adress byte that is transmitted after the preamble is the MSB or LSB.

I've read the datasheet's page 28 and it's not very clear, it just says [b]"Figure 5.shows the packet format with MSB to the left."[/b]

I've also read www.nordicsemi.com/.../How-to-choose-an-address and it says: "First byte of the address should not start with 0x55.. or 0xAA.. as this can be interpreted as part of a preamble, causing an address mismatch for the rest of the address." but still isn't clear if "First byte of the address" is the MSB or LSB of the address.

Hope somebody could answer my question. Thanks.

[Carlos Cuevas]

What would be the best MSB (the one after the preamble, as cleared here) for the address in which the packet-error-rate is minimal?

I just spent 4 hours debugging to find out that my address was the one causing problems.

My application idea is to use 5-byte addressing but leave the MSByte constant for all of my devices, so the "internal" addresses of my sensor network would be 4 bytes long.

I picked 0x48 as the constant MSB and had one device as PRX with address 0x48DDCCBBAA obviously DDCCBBAA was just a made up address to start coding the communication libraries.

I found out that it was a terrible address, near 99% packets lost having the modules about 50cm apart, I switched the address to 0x481D1C1B1A (again, 1D1C1B1A was made up) and suddenly just 20% packets lost (I want to think due to interference with wifi networks around) a huge improvement!

I would like to know what would be the best constant MSByte in order to avoid as much as possible lost packets.

I'm amazed at the suceptibility of the address value. In the field, this address is going to be generated randomly but would greatly appreciate if there are more detailed guidelines about choosing a strong address, maybe some algorithm which determines how strong a given address is, which also explains why some addresses cause high lost package counts.

Thank you very much! Over all, the nRF24L01+ is a great little chip!