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Altera_Forum
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15 years ago

problem with cyclone III and jtag

I would like to put a very serious discussion about using jtag with cyclone III. has cyclone3 less electrical tolerance compared to other FPGA's?????? . we are building a custom board. and t...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

I am implementing a connection as shown in the following reference which shows programming a serial device through JTAG:

Figure 9-30 on page 60 of cyc3_ciii51016-2.pdf

We are using the USB-Blaster cable. I've inserted the 74LVC541 between the connector and the FPGA for the 4 JTAG signals. Pin6 of the JTAG 10 pin connector is a No Connect and Pin 4 is connected to VCCA 2.5V. The pull ups for TDI and TMS are to VCCA 2.5V. Our cycloneIII is configured such that B1 is 3.3V which contains the JTAG signals. The nCONFIG and nSTATUS signals are pulled up as they are in the above reference to VCCIO1(3.3V). The CONF_DONE signal is in B6 and is pulled up to VCCIO6 of 1.5V.

All other connections are exactly as shown in the reference above. Does this capture all your recommendations on how to ensure the FPGA is protected? Did I miss something?