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Bit-banged 56F8013-JTAG does not enter Select-IR-Scan state

Question asked by MARK OKAMURA on Aug 10, 2006
Latest reply on Aug 24, 2006 by Daniel Malik

I am trying to bit-bang the JTAG lines of the 56f8013 with the intent of programming the flash (on another platform). I can communicate with the uP using code warrior and CCS with no problem. I can also bit-bang the JTAG port to enter the the Test-Logic_reset state and retrieve the IDCODE value. (I've verified that the ID is correct.) The problem is that if I reset the TAP, I cannot execute any JTAG instruction, e.g. IDCODE, DEBUG_REQUEST, etc. If I use CW and exit, the 56f8013 remains in a state where I, using my code, can send and receive data just fine. Is there a special sequence after the TAP resets that allows the CW code to communicate (but not my code)? BTW, I used App note 1935 "Programming On-Chip Flash Memories of 56F80X Devices Using the JTAG/OnCE Interface" as a guide.

 

Thanks,
Mark

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