//---------------------------------------------------------------------------------
// Copyright (c) March 2020, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//---------------------------------------------------------------------------------
namespace devMobile.IoT.Rfm9x.RegisterScan
{
   using System;
   using System.Diagnostics;
   using System.Threading;
   using GHIElectronics.TinyCLR.Devices.Spi;
   using GHIElectronics.TinyCLR.Pins;

   public sealed class Rfm9XDevice
   {
      private SpiDevice rfm9XLoraModem;

      public Rfm9XDevice(int chipSelectPin)
      {
         var settings = new SpiConnectionSettings()
         {
            ChipSelectType = SpiChipSelectType.Gpio,
            ChipSelectLine = chipSelectPin,
            Mode = SpiMode.Mode0,
            ClockFrequency = 500000,
            DataBitLength = 8,
            ChipSelectActiveState = false,
         };

         SpiController spiCntroller = SpiController.FromName(FEZ.SpiBus.Spi1);

         rfm9XLoraModem = spiCntroller.GetDevice(settings);
      }

      public Byte RegisterReadByte(byte registerAddress)
      {
         byte[] writeBuffer = new byte[] { registerAddress, 0x0 };
         byte[] readBuffer = new byte[writeBuffer.Length];
         Debug.Assert(rfm9XLoraModem != null);

         rfm9XLoraModem.TransferFullDuplex(writeBuffer, readBuffer);

         return readBuffer[1];
      }
   }

   class Program
   {
      static void Main()
      {
         Rfm9XDevice rfm9XDevice = new Rfm9XDevice(FEZ.GpioPin.D10);

         while (true)
         {
            for (byte registerIndex = 0; registerIndex <= 0x42; registerIndex++)
            {
               byte registerValue = rfm9XDevice.RegisterReadByte(registerIndex);

               Debug.WriteLine($"Register 0x{registerIndex:x2} - Value 0X{registerValue:x2}");
            }
            Debug.WriteLine("");

            Thread.Sleep(10000);
         }
      }
   }
}

Found debugger!

Create TS.

Loading Deployment Assemblies.

Attaching deployed file.

   Assembly: mscorlib (1.0.0.0)  Attaching deployed file.

   Assembly: GHIElectronics.TinyCLR.Devices.Spi (1.0.0.0)  Attaching deployed file.

   Assembly: GHIElectronics.TinyCLR.Devices.Gpio (1.0.0.0)  Attaching deployed file.

   Assembly: GHIElectronics.TinyCLR.Native (1.0.0.0)  Attaching deployed file.

   Assembly: RegisterScan (1.0.0.0)  Resolving.

The debugging target runtime is loading the application assemblies and starting execution.
Ready.

'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\RegisterScan\bin\Debug\pe\..\GHIElectronics.TinyCLR.Native.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\RegisterScan\bin\Debug\pe\..\GHIElectronics.TinyCLR.Devices.Gpio.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\RegisterScan\bin\Debug\pe\..\GHIElectronics.TinyCLR.Devices.Spi.dll'
'GHIElectronics.TinyCLR.VisualStudio.ProjectSystem.dll' (Managed): Loaded 'C:\Users\BrynLewis\source\repos\RFM9X.TinyCLR\RegisterScan\bin\Debug\pe\..\RegisterScan.exe', Symbols loaded.
The thread '<No Name>' (0x2) has exited with code 0 (0x0).
Register 0x00 - Value 0X00
Register 0x01 - Value 0X09
Register 0x02 - Value 0X1a
Register 0x03 - Value 0X0b
Register 0x04 - Value 0X00
Register 0x05 - Value 0X52
Register 0x06 - Value 0X6c
Register 0x07 - Value 0X80
Register 0x08 - Value 0X00
Register 0x09 - Value 0X4f
Register 0x0a - Value 0X09
Register 0x0b - Value 0X2b
Register 0x0c - Value 0X20
Register 0x0d - Value 0X08
Register 0x0e - Value 0X02
Register 0x0f - Value 0X0a
Register 0x10 - Value 0Xff
Register 0x11 - Value 0X70
Register 0x12 - Value 0X15
Register 0x13 - Value 0X0b
Register 0x14 - Value 0X28
Register 0x15 - Value 0X0c
Register 0x16 - Value 0X12
Register 0x17 - Value 0X47
Register 0x18 - Value 0X32
Register 0x19 - Value 0X3e
Register 0x1a - Value 0X00
Register 0x1b - Value 0X00
Register 0x1c - Value 0X00
Register 0x1d - Value 0X00
Register 0x1e - Value 0X00
Register 0x1f - Value 0X40
Register 0x21 - Value 0X00
Register 0x22 - Value 0X00
Register 0x23 - Value 0X00
Register 0x24 - Value 0X05
Register 0x25 - Value 0X00
Register 0x26 - Value 0X03
Register 0x27 - Value 0X93
Register 0x28 - Value 0X55
Register 0x29 - Value 0X55
Register 0x2a - Value 0X55
Register 0x2b - Value 0X55
Register 0x2c - Value 0X55
Register 0x2d - Value 0X55
Register 0x2e - Value 0X55
Register 0x2f - Value 0X55
Register 0x30 - Value 0X90
Register 0x31 - Value 0X40
Register 0x32 - Value 0X40
Register 0x33 - Value 0X00
Register 0x34 - Value 0X00
Register 0x35 - Value 0X0f
Register 0x36 - Value 0X00
Register 0x37 - Value 0X00
Register 0x38 - Value 0X00
Register 0x39 - Value 0Xf5
Register 0x3a - Value 0X20
Register 0x3b - Value 0X82
Register 0x3c - Value 0Xf7
Register 0x3d - Value 0X02
Register 0x3e - Value 0X80
Register 0x3f - Value 0X40
Register 0x40 - Value 0X00
Register 0x41 - Value 0X00
Register 0x42 - Value 0X12