While testing my initial port of the the techfooninja nRF24L01P library to a Wilderness Labs Meadow I noticed that the power level value was a bit odd.

The program '[16720] App.exe' has exited with code 0 (0x0).
 IsPowered: True
 Address: Dev01
 PA: 15
 IsAutoAcknowledge: True
 Channel: 15
 DataRate: DR250Kbps
 Power: 15
 IsDynamicAcknowledge: False
 IsDynamicPayload: True
 IsEnabled: False
 Frequency: 2415
 IsInitialized: True
 IsPowered: True
 00:00:18-TX 8 byte message hello 17
 Data Sent!
00:00:18-TX Succeeded!
 00:00:48-TX 8 byte message hello 48
 Data Sent!

Looking at nRF24L01P datasheet and how this has been translated into code

/// <summary>
///   The power level for the radio.
/// </summary>
public PowerLevel PowerLevel
{
  get
   {
      var regValue = Execute(Commands.R_REGISTER, Registers.RF_SETUP, new byte[1])[1] & 0xF8;
      var newValue = (regValue - 1) >> 1;
      return (PowerLevel)newValue;
   }
  set
   {
      var regValue = Execute(Commands.R_REGISTER, Registers.RF_SETUP, new byte[1])[1] & 0xF8;

      byte newValue = (byte)((byte)value << 1 + 1);

      Execute(Commands.W_REGISTER, Registers.RF_SETUP,
              new[]
                  {
                     (byte) (newValue | regValue)
                  });
   }
}

The power level enumeration is declared in PowerLevel.cs

namespace Radios.RF24
{
    /// <summary>
    ///   Power levels the radio can operate with
    /// </summary>
    public enum PowerLevel : byte
    {
        /// <summary>
        ///   Minimum power setting for the radio
        /// </summary>
        Minimum = 0,

        /// <summary>
        ///   Low power setting for the radio
        /// </summary>
        Low,

        /// <summary>
        ///   High power setting for the radio
        /// </summary>
        High,

        /// <summary>
        ///   Max power setting for the radio
        /// </summary>
        Max,

        /// <summary>
        ///   Error with the power setting
        /// </summary>
        Error
    }
}

No debugging support or Debug.WriteLine in beta 3.7 (March 2020) so first step was to insert a Console.Writeline so I could see what the RF_SETUP register value was.

The program '[11212] App.exe' has exited with code 0 (0x0).
 Address: Dev01
 PowerLevel regValue 00100101
 PowerLevel: 15
 IsAutoAcknowledge: True
 Channel: 15
 DataRate: DR250Kbps
 IsDynamicAcknowledge: False
 IsDynamicPayload: True
 IsEnabled: False
 Frequency: 2415
 IsInitialized: True
 IsPowered: True
 00:00:18-TX 8 byte message hello 17
 Data Sent!
00:00:18-TX Succeeded!

The PowerLevel setting appeared to make no difference and the bits 5, 2 & 0 were set which meant 250Kbps & high power which I was expecting.

The RF_SETUP register in the datasheet, contains the following settings (WARNING – some nRF24L01 registers differ from nRF24L01P)

After looking at the code my initial “quick n dirty” fix was to mask out the existing power level bits and then mask in the new setting.

public PowerLevel PowerLevel
      {
         get
         {
            byte regValue = Execute(Commands.R_REGISTER, Registers.RF_SETUP, new byte[1])[1];;
            Console.WriteLine($"PowerLevel regValue {Convert.ToString(regValue, 2).PadLeft(8, '0')}");
            var newValue = (regValue & 0x06) >> 1;
            
            return (PowerLevel)newValue;
         }
         set
         {
            byte regValue = Execute(Commands.R_REGISTER, Registers.RF_SETUP, new byte[1])[1];
            regValue &= 0b11111000;
            regValue |= (byte)((byte)value << 1);

            Execute(Commands.W_REGISTER, Registers.RF_SETUP,
                    new[]
                        {
                            (byte)regValue
                        });
         }
      }

I wonder if the code mighty be simpler if I used a similar approach to my Windows 10 IoT RFM9X LoRa library

// RegModemConfig1
public enum RegModemConfigBandwidth : byte
{
	_7_8KHz = 0b00000000,
	_10_4KHz = 0b00010000,
	_15_6KHz = 0b00100000,
	_20_8KHz = 0b00110000,
	_31_25KHz = 0b01000000,
	_41_7KHz = 0b01010000,
	_62_5KHz = 0b01100000,
	_125KHz = 0b01110000,
	_250KHz = 0b10000000,
	_500KHz = 0b10010000
}
public const RegModemConfigBandwidth RegModemConfigBandwidthDefault = RegModemConfigBandwidth._125KHz;

...

[Flags]
enum RegIrqFlagsMask : byte
{
	RxTimeoutMask = 0b10000000,
	RxDoneMask = 0b01000000,
	PayLoadCrcErrorMask = 0b00100000,
	ValidHeadrerMask = 0b00010000,
	TxDoneMask = 0b00001000,
	CadDoneMask = 0b00000100,
	FhssChangeChannelMask = 0b00000010,
	CadDetectedMask = 0b00000001,
}

[Flags]
enum RegIrqFlags : byte
{
	RxTimeout = 0b10000000,
	RxDone = 0b01000000,
	PayLoadCrcError = 0b00100000,
	ValidHeadrer = 0b00010000,
	TxDone = 0b00001000,
	CadDone = 0b00000100,
	FhssChangeChannel = 0b00000010,
	CadDetected = 0b00000001,
	ClearAll = 0b11111111,
}

This would require some significant modifications to the Techfooninja library. e.g. the PowerLevel enumeration

namespace Radios.RF24
{
    /// <summary>
    ///   Power levels the radio can operate with
    /// </summary>
    public enum PowerLevel : byte
    {
        /// <summary>
        ///   Minimum power setting for the radio
        /// </summary>
        Minimum = 0b00000000,

        /// <summary>
        ///   Low power setting for the radio
        /// </summary>
        Low = 0b00000010,

        /// <summary>
        ///   High power setting for the radio
        /// </summary>
        High = 0b00000100,

        /// <summary>
        ///   Max power setting for the radio
        /// </summary>
        Max = 0b00000110,
    }
}

I need to do some more testing of the of library to see if the pattern is repeated.