Datasheet

PIC24FV32KA304 FAMILY
DS39995B-page 140  2011 Microchip Technology Inc.
11.1.1 OPEN-DRAIN CONFIGURATION
In addition to the PORT, LAT and TRIS registers for
data control, each port pin can also be individually
configured for either digital or open-drain output. This is
controlled by the Open-Drain Control register, ODCx,
associated with each port. Setting any of the bits
configures the corresponding pin to act as an
open-drain output.
The maximum open-drain voltage allowed is the same
as the maximum V
IH specification.
11.2 Configuring Analog Port Pins
The use of the ANS and TRIS registers control the
operation of the A/D port pins. The port pins that are
desired as analog inputs must have their
corresponding TRIS bit set (input). If the TRIS bit is
cleared (output), the digital output level (V
OH or VOL)
will be converted.
When reading the PORT register, all pins configured as
analog input channels will read as cleared (a low level).
Analog levels on any pin that is defined as a digital
input (including the ANx pins) may cause the input
buffer to consume current that exceeds the device
specifications.
11.2.1 ANALOG SELECTION REGISTER
I/O pins with shared analog functionality, such as ADC
inputs and comparator inputs, must have their digital
inputs shut off when analog functionality is used. Note
that analog functionality includes an analog voltage
being applied to the pin externally.
To allow for analog control, the ANSx registers are
provided. There is one ANS register for each port
(ANSA, ANSB and ANSC). Within each ANSx register,
there is a bit for each pin that shares analog
functionality with the digital I/O functionality.
If a particular pin does not have an analog function, that
bit is unimplemented. See Register 11-1 to Register 11-3
for implementation.
REGISTER 11-1: ANSA: ANALOG SELECTION (PORTA)
U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0
— — — — — — — —
bit 15 bit 8
U-0 U-0 U-0 U-0 R/W-1 R/W-1 R/W-1 R/W-1
— — — — ANSA3 ANSA2 ANSA1 ANSA0
bit 7 bit 0
Legend: U = Unimplemented bit, read as ‘0’
R = Readable bit W = Writable bit HSC = Hardware Settable/Clearable bit
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 15-4 Unimplemented: Read as ‘0’
bit 3-0 ANSA<3:0>: Analog Select Control bits
1 = Digital input buffer is not active (use for analog input)
0 = Digital input buffer is active