Solution ID: rd04232003_5007
Last Modified: Dec 10, 2008
Product Category: Devices
Product Area: I/O
Product Sub-area: Standards

Problem

What is CONFIG_IO?

Solution

CONFIG_IO is a private JTAG instruction supported by Stratix® series and Cyclone® series devices to facilitate the I/O reconfiguration feature.

The CONFIG_IO instruction allows you to access the I/O Configuration Shift Register (IOCSR) via the JTAG BST chain. The instruction code for the CONFIG_IO instruction in Stratix series and Cyclone series devices is 00 0000 1101 (binary) or 00D (hexadecimal).

When it is executed, the TDI will be connected to the beginning of the IOCSR and TDO will be connected to the end of the IOCSR. The user can then shift the new configuration data into the IOCSR to update the I/O standard settings.

For more information on how to use the CONFIG_IO instruction to reconfigure I/O standard settings, please refer to the MorphIO: An I/O Reconfiguration Solution for Altera Devices (PDF) White Paper.

Related Solutions

• Why was the CONFIG_IO JTAG instruction introduced in Quartus II programmer version 4.2 when attempting to configure the FPGA over JTAG and are there any consequences with this change?

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Altera does not warrant that this solution will work for the customer's intended purpose and disclaims all liability for use of or reliance on the solution.