September 26, 2021, 12:04:48 am

LPC2148-s H-JTAG, Keil complication

Started by reuben, January 13, 2013, 08:38:56 pm

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reuben

I have with me the Blueboard-LPC2148-S(http://shop.ngxtechnologies.com/product_info.php?products_id=91)

Schematic: http://www.shop.ngxtechnologies.com/download/stamps/LPC2148_Breakout.pdf

As you can see, this board is just an expansion board, no circuitry is mounted other than LPC2148, 12MHz, 32.768KHz and the associated crystal capacitors.

I've been breaking my head trying to make a JTAG for this board.
Here's the full schematic(http://imgur.com/LBL84,riK8p#0), as well as the H-JTAG setting used(http://imgur.com/LBL84,riK8p#1)

1) THE ENTIRE CIRCUIT IS POWERED OFF A 9V BATTERY STEPPED DOWN TO 3.3V (using LM317T)
2) H-TAG(V2.1) can detect the LPC2148 on parallel port. However, id code returned by LPC2148 is 0x4F1F0F0F, whereas LPC2148 datasheet says it should be 0x0402FF25
3) I am using 74HC244
4) When I start debugging using KEIL Realview, H-TAG reports "Data abort during read"

I have the following corresponding doubts :
1) Is it possible that the circuit is not working because the power source is a 9V battery ?
2) How come LPC2148 returns a wrong code. Is that relevant to JTAG
3) Should I be using 74HCT244, or 74AC244 ?
4) I've read that one should ignore this warning. Is that correct?
5) Should the pull-up resistors be 2K instead of 10k on the JTAG pins?
6) I've seen a schematic where pin 17 of the parallel port is connected to pins 18-25. Is this required ?

I would really appreciate some help