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Lpc2000

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Message

Secondary JTAG problem.

2004-01-20 by Jim Beagley

Hello again,
 I have built a board on which I intend to use the secondary JTAG
functionality to debug my application. However after adding the code
snippet to enable the alternate function for the JTAG pins,Programming
the part using the primary JTAG port, and then moving the connections
from the primary JTAG to the secondary JTAG ports, I encounter the
following problem:

 *** The JTAG will not connect - the following has been observed.

  - Durring reset (ARM LPC2104 reset pin held low) the JTAG signals are   
    seen on the proper lines (Pod tries to contact LPC2104).

  - After releasing the reset line, the processor applies a hard
    pulldown to the JTAG pins, and the POD isn't able to control the
    lines, it tries (evidenced by 300mv signals on proper pins) but
    is simply not able to overcome the pulldown effect.

  - Other code which is in control of other IO pins is running
    correctly so code execution is happening.

----------------------- assumption: ------------

I have made the assumption that since the code 0x554000 has bee placed
into the pinsel1 register, the port direction register has no effect
on the pins any longer.

()()()()() please help.

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