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Solution ID: rd11201998_4611
Last Modified: Oct 01, 2008
Product Category: Devices
Product Area: Configuration
Product Sub-area: JTAG
Problem
How do I read the USERCODE instruction out of Altera devices that support it without using a JAM File or JAM Byte-Code File?
Solution
The USERCODE instruction can be read out of devices simply by loading the JTAG instruction register with the USERCODE instruction and shifting out the 32-bit code.
Reading the USERCODE instruction out of a device is a relatively simple JTAG process. Below is psuedocode that summarizes the process:
- Traverse the JTAG state machine to the Shift-IR state
- Load the USERCODE instruction
- Traverse the JTAG state machine to the Shift-DR state
- Shift out the 32-bit USERCODE value
The easiest way is to obtain the USERCODE is to use Jam™ Files or Jam Byte-Code Files, especially for embedded systems that already implement a Jam Player. The Jam language provides an easy interface to the JTAG port.
Refer to the device family data sheets for information on which devices support the USERCODE instruction. Related Solutions
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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.
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