MCB900: Missing Parts (Q1,C8,C9) on the Board

Information in this article applies to:

• MCB900 Evaluation Boards

QUESTION

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?

ANSWER

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.

MORE INFORMATION

• Refer to Schematics in the MCB900 User's Guide.
• Philips P89LPC932 USERS MANUAL

SEE ALSO

• MCB900: Missing Parts (J2,R7,R8) on the Board

Last Reviewed: Thursday, February 25, 2021