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CONFIGURING FOR THE EXTERNAL CLOCK

Applies to: EPM900 LPC Emulator

Answer


Information in this article applies to:


QUESTION

The external clock is not working with the EPM900 board. What am I doing wrong?

ANSWER

There are several things you must check to ensure you have properly configured your device.

Configuring the Keil IDE

  1. Go to Project — Options for Target — Debug Tab
  2. Select "LPC/EPM900 Emulator Programmer"
  3. Select the Settings button
  4. Change the Oscillator from Internal RC Oscillator to the selected external oscillator. Which oscillator you select depends on your design criteria.

From the P89LPC932 Data Sheet:

More than likely you will be using the Crystal (High Freq) option.

Configuring the EPM900 Board

The 12 MHz crystal on the board is not connected to the P89LPC932 bond out chip; it is used to control the functionality of the board. If you wish to use an external clock, you will have to place your own crystal at the spot marked "user XTAL" next to the "XTAL" jumpers. The capacitors on the board (c8, c9) are 22nF, and are suited for High Frequency crystals.

You must move the XTAL jumpers from INT to EXT in order to use the additional crystal you placed on the board.

You can only use the external crystal during emulation, not during programming.

MORE INFORMATION

SEE ALSO

Article last edited on: 2006-11-30 10:37:55

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