DS51795A Datasheet, PDF (71/98 Pages) Microchip Technology – PICkit™ 3 Programmer/Debugger

PICkit™ 3 USER’S GUIDE
Appendix B. Operational Advisory
When designing applications that use the PICkit 3, these operational issues should be
considered:
• Oscillator Circuit Setup
• ICSP™ Implementation and Considerations
• Recommended Configuration
• Alternate Configuration
• Communication Channel
• Grounding and AC Applications
• Correcting Crosstalk
• Hibernation
OSCILLATOR CIRCUIT SETUP
Primary Oscillator
Often differences between the MPLAB IDE default settings and the unique target
requirements cause the following message to display in the output window “The target
device is not ready for debugging. Please check your configuration bit settings and pro-
gram the device before proceeding.” To correct this, set the Configuration bits to match
the oscillator setting of the target configuration.
For debugging operations, the application (target) oscillator must be functioning before
in-circuit debugging can take place. Ensure the oscillator configuration and the MPLAB
IDE Configuration bit setup are configured properly. For example, if your application
uses a 20 MHZ crystal oscillator, select the HS (High Speed) selection in MPLAB IDE.
For any other applicable device oscillator modes, consult the device data sheet.
Crystal Oscillator
If the MPLAB ICD header or processor extension packs are used to connect to the
target, there may be problems with starting the crystal resonator. To avoid potential
problems, consider the following:
1. Ensure the crystal is connected near the device footprint.
2. Keep all lines as short as possible in the target application without unnecessary
discontinuities such as PCB vias and test points.
3. Minimize any capacitive loading on these nodes.
4. Avoid using a socket for the placement of the crystal and capacitor. Solder the
devices directly to PCB pads.
ICSP™ IMPLEMENTATION AND CONSIDERATIONS
The PICkit 3 uses a serial signaling scheme to program and debug a target device. The
signals utilized are a clock and a data signal. In most devices they are also mapped to
a port (typically RB6 and RB7), but they are also defined in some data sheets as PGC
and PGD or ICSPCLK and ICSPDAT.
© 2009 Microchip Technology Inc.
DS51795A-page 67