Microchip Technology MA330031-2 Data Sheet
2011-2013 Microchip Technology Inc.
DS70000657H-page 31
dsPIC33EPXXXGP50X, dsPIC33EPXXXMC20X/50X AND PIC24EPXXXGP/MC20X
2.5
ICSP
Pins
The PGECx and PGEDx pins are used for ICSP and
debugging purposes. It is recommended to keep the
trace length between the ICSP connector and the ICSP
pins on the device as short as possible. If the ICSP con-
nector is expected to experience an ESD event, a
series resistor is recommended, with the value in the
range of a few tens of Ohms, not to exceed 100 Ohms.
Pull-up resistors, series diodes, and capacitors on the
PGECx and PGEDx pins are not recommended as they
will interfere with the programmer/debugger communi-
cations to the device. If such discrete components are
an application requirement, they should be removed
from the circuit during programming and debugging.
Alternatively, refer to the AC/DC characteristics and
timing requirements information in the respective
device Flash programming specification for information
on capacitive loading limits and pin Voltage Input High
(V
debugging purposes. It is recommended to keep the
trace length between the ICSP connector and the ICSP
pins on the device as short as possible. If the ICSP con-
nector is expected to experience an ESD event, a
series resistor is recommended, with the value in the
range of a few tens of Ohms, not to exceed 100 Ohms.
Pull-up resistors, series diodes, and capacitors on the
PGECx and PGEDx pins are not recommended as they
will interfere with the programmer/debugger communi-
cations to the device. If such discrete components are
an application requirement, they should be removed
from the circuit during programming and debugging.
Alternatively, refer to the AC/DC characteristics and
timing requirements information in the respective
device Flash programming specification for information
on capacitive loading limits and pin Voltage Input High
(V
IH
) and Voltage Input Low (V
IL
) requirements.
Ensure that the “Communication Channel Select” (i.e.,
PGECx/PGEDx pins) programmed into the device
matches the physical connections for the ICSP to
MPLAB
PGECx/PGEDx pins) programmed into the device
matches the physical connections for the ICSP to
MPLAB
®
PICkit™ 3, MPLAB ICD 3, or MPLAB
REAL ICE™.
For more information on MPLAB ICD 2, ICD 3 and
REAL ICE connection requirements, refer to the
following documents that are available on the
Microchip web site.
• “Using MPLAB
For more information on MPLAB ICD 2, ICD 3 and
REAL ICE connection requirements, refer to the
following documents that are available on the
Microchip web site.
• “Using MPLAB
®
ICD 3”
(poster) DS51765
• “MPLAB
®
ICD 3 Design Advisory”
DS51764
• “MPLAB
®
REAL ICE™ In-Circuit Emulator User’s
Guide”
DS51616
• “Using MPLAB
®
REAL ICE™
In-Circuit Emulator”
(poster) DS51749
2.6
External Oscillator
Pins
Many DSCs have options for at least two oscillators: a
high-frequency Primary Oscillator and a low-frequency
Secondary Oscillator. For details, see
high-frequency Primary Oscillator and a low-frequency
Secondary Oscillator. For details, see
for details.
The oscillator circuit should be placed on the same
side of the board as the device. Also, place the
oscillator circuit close to the respective oscillator pins,
not exceeding one-half inch (12 mm) distance
between them. The load capacitors should be placed
next to the oscillator itself, on the same side of the
board. Use a grounded copper pour around the
oscillator circuit to isolate them from surrounding
circuits. The grounded copper pour should be routed
directly to the MCU ground. Do not run any signal
traces or power traces inside the ground pour. Also, if
using a two-sided board, avoid any traces on the
other side of the board where the crystal is placed. A
suggested layout is shown in
side of the board as the device. Also, place the
oscillator circuit close to the respective oscillator pins,
not exceeding one-half inch (12 mm) distance
between them. The load capacitors should be placed
next to the oscillator itself, on the same side of the
board. Use a grounded copper pour around the
oscillator circuit to isolate them from surrounding
circuits. The grounded copper pour should be routed
directly to the MCU ground. Do not run any signal
traces or power traces inside the ground pour. Also, if
using a two-sided board, avoid any traces on the
other side of the board where the crystal is placed. A
suggested layout is shown in
FIGURE 2-3:
SUGGESTED PLACEMENT
OF THE OSCILLATOR
CIRCUIT
OF THE OSCILLATOR
CIRCUIT
Main Oscillator
Guard Ring
Guard Trace
Oscillator Pins