Strange Behavior, LPC2138, ARM-USB-OCD, NoIce

Development Boards MicroMod
1

I’ve can successfully download and debug code created with the ImageCraft compiler as long as I don’t have anything connected to outputs p0.18 and p0.20.

If I have something connected then OpenOCD won’t even start. If I leave it disconnected until after the flash is loaded and the debugger starts OpenOCD will crash as soon as I connect to those pins.

My board (Embedded Artists) has LEDs on those lines. If nothing is connected the LEDs for those lines flash while NoICE is burning the flash.

Why does JTAG/OpenOCD have anything at all to do with those lines?

Is the LPC2138 trying to do something with the secondary SPI port?

2

The Embedded Artists QuickStart Prototype Board has some jumpers hidden under my LPC2138 processor board.

Yup. Those jumpers connect the JTAG signals to p0.17 through p0.21 for use with the LPC2104/05/06 microcontrollers.

I removed the jumpers and all is well.

I’ve been telling people for 30+ years to always check their assumptions. Sometimes I even remember to do it myself.