|ARM Technical Support Knowledge Articles|
Applies to: MCB900 Evaluation Board
Information in this article applies to:
I have the MCB900 board, but the parts Q1 (XTAL), C8, and C9 are empty. Do I need to add these parts before using the board? Why are these parts missing?
The Philips P89LPC932 has very powerful clock options that are defined in the register UCFG1 with the FOSC field:
FOSC Oscillator Configuration ----------------------------- 111 External clock input on XTAL1. 100 Watchdog Oscillator, 400 kHz (+20/ -30% tolerance). 011 Internal RC oscillator, 7.373 MHz ±2.5%. 010 Low frequency crystal, 20 kHz to 100 kHz. 001 Medium frequency crystal or resonator, 100 kHz to 4 MHz. 000 High frequency crystal or resonator, 4 MHz to 12 MHz.
By default, the MCB900 board is configured for Internal RC oscillator. This allows you to use the XTAL pins as standard I/O pins. There is no need to add an external XTAL unless you program the device for using an off-chip (external) crystal. So the board gives you the option to add an external clock source of your choice when needed.
You may add an external XTAL (typically 12MHz) and external capacitors C8 and C9 (typically 22pF) to the board if you want to use an off-chip clock source. The board has several options to add these parts.
Article last edited on: 2006-11-30 12:17:07
Did you find this article helpful? Yes No
How can we improve this article?