MCB2103: Port LEDs do not Display as Expected

Information in this article applies to:

• MCB2103 Evaluation Boards

QUESTION

I'm using the MCB2103 and I'm having problems with P0.17 and P0.18 as GPIO; the ports appear stuck low (LEDs on MCB2103 always off). I can't write 1's to the ports and the BLINKY examples don't wiggle these pins either. I traced through the hardware and found nothing wrong. What could be causing this?

ANSWER

The current user manual for the LPC2103 states that these pins (P0.17 and P0.18) are always "open drain". If you want to use them as outputs driving HIGH, add two pull-up resistors (e.g. 10K) to these pins when connecting them to 3.3V.

MORE INFORMATION

• Refer to LEDs in the MCB2103 User's Guide.
• LPC2101/LPC2102/LPC2103 User Manual

SEE ALSO

• MCB2103: Device may fail at High Clock Speeds

Last Reviewed: Wednesday, October 14, 2020