How decode RSSI message

[Carlos Ramos]

I use the NRF 24AP2E in my communications, and I need detect if the communication is good. I active the RSSI message, but in scanning mode I don't receive byte 0x20 in Measurement Type (in ANT protocol information indicates that the RSSI value field shield not be interpreted), horever I see the values change because the proximity of devices.

The procedure that I do is the following:

0001 -TX- A40342004000A5 - Assign Channel
0002 -RX- A40340004200A5
0003 -TX- A405510000000503F6 - Channel ID
0004 -RX- A40340005100B6
0005 -TX- A4026E00C008 - ListLib
0006 -RX- A40340006E0089
0007 -TX- A402450003E0 - Channel RF Frequency
0008 -RX- A40340004500A2
0009 -TX- A4015B00FE - Open Rx Scan Mode
000A -RX- A40340005B00BC
000B -RX- A4124E000000000000000000C00046050310016C0005
000C -RX- A4124E000000000000000000C00043050310016D0001
000D -RX- A4124E000000000000000000C00045050310016D0007
000E -RX- A4124E000000000000000000C0004405031000690003
000F -RX- A4124E000000000000000000C00046050310016C0005
0010 -RX- A4124E000000000000000000C00043050310016D0001
0011 -RX- A4124E000000000000000000C00045050310016D0007
0012 -RX- A4124E000000000000000000C0004405031000690003
0013 -RX- A4124E000000000000000000C00046050310016C0005
0014 -RX- A4124E000000000000000000C00043050310016D0001
0015 -RX- A4124E000000000000000000C00045050310016D0007
0016 -RX- A4124E000000000000000000C0004405031000690003
0017 -RX- A4124E000000000000000000C00046050310016C0005
0018 -RX- A4124E000000000000000000C00043050310016D0001
0019 -RX- A4124E000000000000000000C00045050310016D0007
001A -RX- A4124E000000000000000000C0004405031000680002

I receive value 10-01-6C-00, 10 represent measurement type, 01 is RSSI value and 6C is Threshold Configuration, and 00 I don't know, can explain the values?

I see the values of RSSI is beetween 0(closest device) and 1(farthest device), and Threshold Configuration beetween 68(closest device) and 6D(farthest device).

What is the correct procedure to obtain the values ​​of RSSI?

[Asbjørn]

For the nRF24AP2 there is only a 1-bit RSSI available. So the receiver can measure if the power in the receive channel is above or below -64 dBm and hence you have either on or off. So the measurement type will be different as the RSSI is only available on ANT devices based on the nRF51422. So on the nRF24AP2 there's no real RSSI, but if I am to guess since the ANT protocol was developed by Dynastream, I would guess that they also play around with the output power on the sender to see how that affects the 1 bit RSSI on the AP2. This is just my guess though as I'm not sure on what the threshold part of the RSSI extended measurement means.

Proximity search: www.thisisant.com/.../an12-proximity-search

RSSI extended info: www.thisisant.com/.../an16-rssi-extended-information