You are here

How to use JTAG EXTEST ? | Cypress Semiconductor

How to use JTAG EXTEST ?

Summary: 4 Replies, Latest post by knight_camper_1861791 on 12 Sep 2016 12:36 PM PDT
Verified Answers: 1
Last post
Log in to post new comments.
knight_camper_1861791's picture
User
4 posts

Hello,

I'm currently trying to use JTAG EXTEST instruction to characterize a custom component attach to my CY8C5287AXI-LP095 (TQFP 100) without any success

Reading at the BSDL file (CY8C58LPXXX_TQFP100_4JTAG.bsdl) it's written:

This CY8C58LPXXX TQFP100 BSDL file supports 1149.1 testing only after two of the following conditions are satisfied:

1. The JTAG port is enabled.

2. All IOs are pre-configured to drive out fast strong high/low.

JTAG access can be enabled either through programming NV-Latch bits appropriately or through using test-port acquisition protocol. The IOs may be pre-configuration either by writing port configuration registers directly through a test port, or relying on a programmed boot sequence which does that to complete automatically. Testing other IO configurations requires changes to this file and the pre-configured IO configuration.

JTAG is enable by default on chip from factory, and I have successfully achieve accessing IO configuration register and output value register (succesfully toggle a LED) through the jtag chain using programming svf file generated adding access to those register.

However after doing so I'm still not able to use Sample/Preload and Extest jtag instruction.
Does anybody know something I may miss or could provide an example of SVF file achieving this ?

Thanks

Geona Mary's picture
Cypress Employee
7 posts

Hi,

Since you are able to toggle LED JTAG is enabled and also IO port is strong mode. Can you post JTAG command sequence you are using and also error messages if any you are getting ?

knight_camper_1861791's picture
User
4 posts

Hello,

Thanks for your answer it takes time for me to add comments in my svf file.
Please find attach.
So as I said within I toggle the IO with the IO register.
And I'm looking for a way to use properly EXTEST mode of JTAG.

Attachments: 
knight_camper_1861791's picture
User
4 posts

Hello,

This is my attempt to set the EXTEST instruction in TC TAP

I don't see any wrong with my approach maybe some one else will.

knight_camper_1861791's picture
User
4 posts

Update.

If I add the code to shift PRELOAD instruction and EXTEST to the toggleled.svf, the led is still on while PRELOAD instruction is load and BSR loaded with SDR. As soon as I shift EXTEST Led turn off and if I shift all one in all BSR register with SDR intruction the led remain off.

Could this be because I only Set drive mode to strong on psoc port 3 and not all port ?

Log in to post new comments.