User manual

Operation

Not all devices have the AVDD and AVSS lines, but if they are present on the target

device, all must be connected to the appropriate levels in order for the emulator to

operate.

In general, it is recommended per device data sheet that all V

DD/AVDD and VSS/AVSS

lines be connected to the appropriate levels. Also, devices with a V

CAP pin (like

PIC18FXXJ devices) should be connected to the appropriate capacitor or other internal

regulator device.

2.4.4 Circuits That Will Prevent the Emulator From Functioning

Figure 2-9 shows the active emulator lines with some components that will prevent the

MPLAB REAL ICE in-circuit emulator system from functioning.

FIGURE 2-9: IMPROPER CIRCUIT COMPONENTS

Specifically, these guidelines must be followed:

• Do not use pull-ups on PGC/PGD – they will divide the voltage levels, since these

lines have 4.7 kΩ pull-down resistors in the emulator.

• Do not use capacitors on PGC/PGD – they will prevent fast transitions on data

and clock lines during programming and debug communications.

• Do not use capacitors on MCLR

– they will prevent fast transitions of VPP. A

simple pull-up resistor is generally sufficient.

• Do not use diodes on PGC/PGD – they will prevent bidirectional communication

between the emulator and the target device.

For other operational issues, see:

• Chapter 10. “Error Messages”

• Chapter 9. “Frequently Asked Questions (FAQ)”

• Section 10.3.6 “Debug Failure Actions” (Top Reasons Why You Can’t Debug)

• Section 12.8 “Loop-Back Test Board”

Note: The interconnection is very simple. Any problems experienced are often

caused by other connections or components on these critical lines that

interfere with the operation of the MPLAB REAL ICE in-circuit emulator

system, as discussed in the next section.

No!

VPP/MCLR

PGC

PGD

Interface

Connector

ACTIVE

STATUS

RESETFUNCTION

Emulator Pod