Datasheet
Operation
2013 Microchip Technology Inc. DS52085A-page 33
3.5.3 Target Connection Circuitry
Figure 3-8 shows the interconnections of the MPLAB REAL ICE in-circuit emulator to
the connector on the target board. The diagram also shows the wiring from the connec-
tor to a device on the target PC board. A pull-up resistor (typically 10 k) is recom-
mended to be connected from the V
PP/MCLR line to VDD so that the line may be
strobed low to reset the device.
FIGURE 3-8: STANDARD CONNECTION TO TARGET CIRCUITRY
In the following descriptions, only three lines are active and relevant to core emulator
operation: pins 1 (V
PP/MCLR), 5 (PGC) and 4 (PGD). Pins 2 (VDD) and 3 (VSS) are
shown on the above diagram for completeness, but are only sensed, not provided or
controlled, by the emulator.
Be aware that the target V
DD is sensed by the emulator to allow level translation for tar-
get low-voltage operation and to detect a device. If the emulator does not sense voltage
on its V
DD line (pin 2 of the interface connector), it will not connect with the device.
Not all devices have the AV
DD 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 oper-
ate. This also applies to voltage regulator pins (e.g., ENVREG/DISVREG on PIC24FJ
MCUs).
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 (e.g.,
PIC18FXXJ devices) should be connected as close to the device as possible and to the
appropriatly-valued capacitor or other internal regulator device. See your device data
sheet for proper values.
VDD
VPP/MCLR
PGC
PGD
V
SS
AVDD**
AVSS**
2
1
5
4
3
Ta rg e t V
DD
4.7K-10K
Application
PC Board
Device
ACTIVE
STATUS
RESETFUNCTION
Emulator Pod
XTAL*
(typical)
* Target device must be running with an oscillator for the emulator to function
as a debugger.
** If the device has AVDD and AVSS lines, they must be connected for
the emulator to operate.
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 sys-
tem, as discussed in the next section.