Adafruit Product Code: 2724
The new and improved Programmer Shield is essentially a USB-JTAG converter that gives advanced users complete access to the Photon's memory space. It supports openOCD and the WICED SDK, and is built around the FT2232H high speed USB FIFO.
Unlike the previous Programmer Shield, it is fully standalone and requires no third-party programmers.
In addition to providing a JTAG interface, this shield can also act as a USB to Serial converter. You can also use this shield as a generic JTAG programmer for your other projects!
Designed for use with the Photon, backwards compatible with the Core.