48GA004 datasheet(23/268 Pages) MICROCHIP

23 / 268 page

 2010 Microchip Technology Inc.

DS39881D-page 23

PIC24FJ64GA004 FAMILY

2.7

Configuration of Analog and

Digital Pins During ICSP

Operations

If an ICSP compliant emulator is selected as a debug-

ger, it automatically initializes all of the A/D input pins

(ANx) as “digital” pins. Depending on the particular

device, this is done by setting all bits in the ADnPCFG

All PIC24F devices will have either one or more

ADnPCFG registers or several ANSx registers (one for

each port); no device will have both. Refer to

Section 21.0 “10-Bit High-Speed A/D Converter”

for

more specific information.

The bits in these registers that correspond to the A/D

pins that initialized the emulator must not be changed

the

user

application

firmware;

otherwise,

communication errors will result between the debugger

and the device.

If your application needs to use certain A/D pins as

analog input pins during the debug session, the user

application must modify the appropriate bits during

initialization of the ADC module, as follows:

• For devices with an ADnPCFG register, clear the

bits corresponding to the pin(s) to be configured

as analog. Do not change any other bits, particu-

larly those corresponding to the PGECx/PGEDx

pair, at any time.

• For devices with ANSx registers, set the bits

corresponding to the pin(s) to be configured as

analog. Do not change any other bits, particularly

those corresponding to the PGECx/PGEDx pair,

at any time.

When a Microchip debugger/emulator is used as a

programmer, the user application firmware must

correctly configure the ADnPCFG or ANSx registers.

Automatic initialization of this register is only done

during debugger operation. Failure to correctly

configure the register(s) will result in all A/D pins being

recognized as analog input pins, resulting in the port

value being read as a logic '0', which may affect user

application functionality.

2.8

Unused I/Os

Unused I/O pins should be configured as outputs and

driven to a logic low state. Alternatively, connect a 1 kΩ

to 10 kΩ resistor to VSS on unused pins and drive the

output to logic low.

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