Microchip Technology MA330016 Data Sheet
© 2007-2011 Microchip Technology Inc.
DS70290J-page 15
dsPIC33FJ32GP202/204 and dsPIC33FJ16GP304
2.5
ICSP Pins
The PGECx and PGEDx pins are used for In-Circuit
Serial Programming (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 connector 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 input voltage high
(V
Serial Programming (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 connector 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 input voltage high
(V
IH
) and 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
®
ICD 3 or MPLAB REAL ICE™ in-circuit
emulator.
For more information on MPLAB ICD 3 or MPLAB
REAL ICE™ in-circuit emulator connection
requirements, refer to the following documents that are
available on the Microchip web site.
• “Using MPLAB
For more information on MPLAB ICD 3 or MPLAB
REAL ICE™ in-circuit emulator 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™” (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 (refer to
high-frequency primary oscillator and a low-frequency
secondary oscillator (refer to
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
13
Main Oscillator
Guard Ring
Guard Trace
Secondary
Oscillator
Oscillator
14
15
16
17
18
19
20