RAM programming by JTAG (i need some serious help)

Hi. I am not sure how your particular FPGA implements its JTAG interface, but you can probably obtain control of the pins on the FPGA (the ones that connect to your RAM) by clocking in and out serial data through the JTAG port (IEEE 1149.1 standard). I used a homemade substitute of the parallell-programmer to write data into flash memories attached to a MCU this way. I rewrote the code found on

to suit my particular hardware configuration.

Hope this helps you find a solution.

Redards Daniel Nilsson

You can purchase boundary scan software tools from Universal Scan that can do this. See

for details.

John

We're using Eclipse from Intellitech for doing this. It works with Xilinx cables. The software has models of SRAMs and FLASH in a library for automatically performing uploads/downloads to/from memories connected to an FPGA.

There's also a memory test feature to check the connections before trying to program and it gives really good diagnostics to find the open pins. If speed is important you might also want a faster jtag controller. we use It's expensive though, compared to Xilinx, US$2K, but is faster and has some digital inputs and outputs which can speed up FLASH programming.

Subra