Microchip Technology MPLAB ICE, Руководство пользователя

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MPLAB
®
ICE User’s Guide
DS51159B-page 86

2001 Microchip Technology Inc.
4.7 Setting Up the Processor Clock
MPLAB ICE can use the on-board clock with either emulator or target power,
or it can use the target board clock with target board power.
4.7.1 Using the On-board Clock
MPLAB ICE has an on-board clock that can be programmed to a frequency
between 32 kHz and 40 MHz. To program the clock, select the Clock tab on
the Development Mode dialog.
Figure 4.6: Development Mode Dialog – Clock Tab, On-Board Clock
First, select the Oscillator Type based on your desired frequency range. Refer
to the specific device’s data sheet to determine the supported frequency
range for each oscillator type.
Next, select the Desired Frequency magnitude (MHz, kHz, or Hz), enter the
Desired Frequency, and click Apply. The clock will then be programmed to
operate as close to that frequency as possible. Since the generated clock
frequency will be slightly different than the desired clock frequency, the Actual
Frequency will be displayed. The Actual Frequency will be within 0.5% of the
desired frequency.
To verify the clock frequency, you can measure the trigger output pulse of the
TRIGOUT logic probe (Section B.6) and divide by 4.
4.7.2 Using a Target Board Clock
MPLAB ICE can use the processor clock on the target board as long as target
board (external) power is being used. It can determine the frequency (to
within 3.5%) of the target board clock and use it for displaying timing
information.