HOWTO: The!Cart CPLD logic update via JTAG

Note: official CPLD logic releases can be downloaded from here.
Starting with version 260322 you can find further information and update instructions in the README.txt file included in the release ZIP.

Open the cart shell, the top layer of the PCB looks like this:

Note that the LEDs are on the front. The JTAG connector is located in the top left

Here's a detailled picture of the JTAG connector, with pin assignment:

Note: there are 8 unpopulated holes for the JTAG connection, unfortunately they are located too near to the edge of the PCB - if you solder in a standard (either 90 degrees or straight) header connector the PCB won't fit into the cart shell. It's best to use a stick a standard 2.54mm 8-pin header through the holes and hold it in place at a slight angle so that the pins make contact.

Step-by-step update instructions

• Plug the PCB into the cart slot with the LEDs facing towards you (in case of XL or XEGS) or upwards (in case of XE). Also be sure to insulate the PCB so that the metal door of the XL cart slot can't touch the PCB - otherwise you'll have a short circuit and both your Atari and The!Cart could be damaged.
• Connect your JTAG cable.
• Power on the Atari.
• Use your JTAG programmer software to update the Xilinx XC95144XL CPLD with TheCart.jed. While doing that hold the JTAG header connector at an angle to ensure you have a good connection.
• Alternative update method: program TheCart.svf using an SVF capable programmer, for example OpenOCD on a Raspberry Pi or UrJTAG.
• Power off the Atari and remove the JTAG cable.
• Power the Atari on again to verify that everything works fine.
• Unplug The!Cart and reassemble the cartridge shell.