The rfm69hw I measured isn't quite that simple. I get about 1.1 db higher output using 16-31 vs 0-15.
Also, if I use just PA1 instead of PA1+PA2, 0-15 has no output and 16-31 ranges from -2 to 13 dbm.
So if the power is in 1 dB steps, but the difference between the 0-15 and 16-31 ranges is 1.1 dB, should these values be used to go from lowest to highest power?
0, 1, 16, 2, 17, 3, 18, 4, 19, 5, 20, 6, 21, 7, 22, 8, 23, 9, 24, 10, 25, 11, 26, 12, 27, 13, 28, 14, 29, 15, 30, 31.
OK, perhaps a bit silly just to have the little 0.1 dB steps between the 0-15 and 16-31 settings, but this would give a 0-31 range just like the RFM69W so calls to setPowerLevel would be the same.
To take it further, perhaps setPowerLevel for the RFM69HW could use PA1 and PA1+PA2 modes to get a +2 to +20 dBm.