A Quick JTAG ISP Checklist

Most Xilinx CPLDs, PROMs, and FPGAs have an IEEE Standard 1149.1 (JTAG) port. Xilinx devices with a JTAG port are in-system programmable (ISP) through the JTAG port. The ISP feature is beneficial for fast prototype development. This application note describes a short list of considerations needed to get the best performance from your ISP designs. The list of considerations generally applies to all Xilinx ISP device families. Special considerations for Xilinx CPLDs are highlighted.All JTAG-capable devices on a board can be connected in a single JTAG device daisy-chain enabling JTAG software to control multiple devices through a single JTAG cable connection. Thus, the Xilinx iMPACT software can in-system program all Xilinx CPLDs, PROMs, and FPGAs on a board through a Xilinx JTAG cable.