Device Family: Intel® Cyclone®, Intel® Stratix®

Type: Answers

Area: Component

Error: “Can’t access JTAG chain”


You may a receive this error message during auto-detect possibilty due to a download cable problem, TDO is not connected properly, a noisy TCK signal, or TDI shorted to GND.

Here are some suggested steps for resolving the issue:

  1. Make sure the pull-up and pull-down resistors connected to the JTAG pins are following the recommended values as stated in the respective device handbook. 
  2. Check the JTAG chain connectivity and the integrity of the TCK signal. Altera recommends pulling the TCK pin low through a pull-down resistor. Also make sure the TCK signal is clean to avoid any programming or JTAG configuration failure.
  3. Use another USB-Blaster™ or other download cable. This is to ensure that the download cable is functioning.
  4. Check the voltage seen on the pins of the JTAG header to see if they are at appropriate levels. The download cable is powered by the board, so ensure your board is properly powered.
  5. Ensure all power supplies to the device are within recommended operating conditions. Refer to the respective device handbook for the correct voltage level.