Re: What's the problem with my JTAG?????

Started by "Milender, Jeff" December 13, 2007
We ran into a similar problem on the LPC2294 (No JTAG function) and it
turned out that we were inadvertently causing the micro to enter an
undocumented test mode which disabled the JTAG due to a failed CAN

In our case on the LPC2294 it was caused by holding TD1 (pin22) low at
reset. Below is what we got from NXP for the LPC2294

As far as other "magic pins", here is a list for the LPC2294:
- pin 22: low at reset invokes a factory test mode <-- This is the one
the caused us problems due to a failed CAN Transceiver
- P0.14: low at reset invokes on-chip bootloader
- P1.20: low at reset enables ETM pins (P1.16 - P1.25)
- P1.26: low at reset enables JTAG pins (P1.26 - P1.31)
- P2.26 + P2.27: BOOT0 + BOOT1 pins state at reset control default
memory operation
Jeff Milender
Sr. Electronic Design Engineer
Cargo Systems
Goodrich Interiors
2604 Highway 20 North
Jamestown, ND 58401
Tel: 701-253-7569


From: l... [mailto:l...] On Behalf
Of karelvergauwe
Sent: Thursday, December 13, 2007 4:08 AM
To: l...
Subject: [lpc2000] Re: What's the problem with my JTAG?????

Perhaps you can program it with some other port. Serial, USb or
ethernet perhaps??? For serial use Flash Magic.

An Engineer's Guide to the LPC2100 Series