There are probably a few ways of going about doing this, but this is the way that worked for me. These instructions are mainly from https://learn.adafruit.com/downloads/pdf/getting-started-with-the-lpc810.pdf The main page about James' LPC810 node can be found at LPC810 based node
Download & Install LPCXpresso - http://www.lpcware.com/lpcxpresso/downloads/windows
Download & Install Flash Magic - http://www.flashmagictool.com/
LPC810 UKHASnet Codebase - https://github.com/jamescoxon/LPC810
(I had installed the arm-none-eabi-gcc compiler prior to this from James' instructions, but I think LPCXpresso comes with a compiler anyway)
Download the LPC810 codebase from James' github by clicking the “Download ZIP” button on the web page.
To get LPCXpresso to play ball, you need a couple of “project” files from https://github.com/microbuilder/LPC810_CodeBase. Simply copy .cproject and .project into James' zip using something like winrar. The file structure inside the zip should now look like this:
Fire up LPCXpresso (You may need to activate it if this is your first time) Click “Import Project” from the left hand pane:
Browse to the zip we just added the above files to then click Next:
Ensure that “LPC810_CodeBase” is checked then click Finish.
All being well you should then be able to browse to src/main.c on the “Project Explorer” left hand pane. You will then need to edit the node specific details outlines in the main LPC810 wiki page:
Save the file then click Project > Build All. A few seconds later you should have a .hex in your Release/ folder.
Connect your USB-TTL adapter as below:
Note that on some USB-TTL boards the RX and TX are marked the wrong way around. If you are struggling to upload code, try swapping RX/TX. If you are powering the board from the USB-TTL adapters 3.3v rail, it might not be able to supply enough current for the LPC AND RFM. Try installing a regulator and decoupling capacitors then power from 5v.
Start up Flash Magic, browse to the above .hex file and fill out the rest of the settings according to this image (selecting the correct com port for your usb-ttl adapter):
With the two right hand pins on the top header shorted, cycle the power to the board by disconnecting and reconnecting VCC and GND. This will put it into programming mode. Click start on Flash Magic. Hopefully now a progress bar will appear at the bottom and the board will be flashed in a few seconds. If you get an autobauding error message, check the above tips about swapping rx/tx etc.
Disconnect the short between pins 3&4 on the header, then move the cable from pin 2 over to pin 3. Connect to the COM port at 115200 baud using putty or the arduino serial monitor then power cycle the board. You should see “done” appear as the board boots. Packets should pop up at 869.500MHz every 200 seconds which you can check with an SDR.