SWRS046H – NOVEMBER 2006 – REVISED MARCH 2015
0.5 ms of delay between each RSSI read.
12. Write XP – 2 × DX to PHASE_COMP register.
13. Wait at least 3 ms. Measure signal strength Y0 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
14. Set AP = 2 × (Y0 – Y2 + Y4) – (Y1 + Y3).
15.
If AP > 0 then
set DP = ROUND ( 7 × DX × (2 × (Y0 – Y4) + Y1 – Y3) / (10 × AP))
else
if Y0 + Y1 > Y3 + Y4 then
set DP = DX
else
set DP = –DX.
16.
If DP > DX then
set DP = DX
else
if DP < –DX then set DP = –DX.
17. Set XP = XP + DP.
18. Write XP to PHASE_COMP register.
19.
If XG + 2 × DX < 127 then
write XG + 2 × DX to GAIN_COMP register
else
write 127 to GAIN_COMP register.
20. Wait at least 3 ms. Measure signal strength Y4 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
21. Write XG + DX to GAIN_COMP register.
22. Wait at least 3 ms. Measure signal strength Y3 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
23. Write XG to GAIN_COMP register.
24. Wait at least 3 ms. Measure signal strength Y2 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
25. Write XG – DX to GAIN_COMP register.
26. Wait at least 3 ms. Measure signal strength Y1 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
27. Write XG – 2 × DX to GAIN_COMP register.
28. Wait at least 3 ms. Measure signal strength Y0 as filtered average of 8 reads from RSSI register with
0.5 ms of delay between each RSSI read.
29. Set AG = 2 × (Y0 – Y2 + Y4) – (Y1 + Y3).
30.
If AG > 0 then
set DG = ROUND (7 × DX × (2 × (Y0 – Y4) + Y1 – Y3) / (10 × AG)
else
if Y0 + Y1 > Y3 + Y4 then
set DG = DX
else
set DG = –DX.
31.
If DG > DX then
set DG = DX
else
if DG < –DX then set DG = –DX
32. Set XG = XG + DG.
33. If DX > 1 then go to step 2.
34. Write XP to PHASE_COMP register and XG to GAIN_COMP register.
If repeated calibration gives varying results, try to change the input level or increase the number of RSSI
reads N. A good starting point is N = 8. As accuracy is more important in the last fine-calibration steps, it
can be worthwhile to increase N for each loop iteration.
Copyright © 2006–2015, Texas Instruments Incorporated
Detailed Description
33
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