AN 425: Using the Command-Line Jam STAPL Solution for Device Programming

ID 683089
Date 12/09/2016
Document Table of Contents

1.6.2. Use a Pull-Down Resistor on the TCK Signal

You must hold the TCK signal low using a pull-down resistor to keep the JTAG test access port (TAP) in a known state at power-up.

A missing pull-down resistor can cause a device to power-up in the state of JTAG and its boundary-scan test (BST). This situation can cause conflicts on the board.

A typical resistor value is 1 kΩ.