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PIC24FV32KA304 FAMILY
DS39995C-page 210
2011-2012 Microchip Technology Inc.
22.1
A/D Control Registers
The 12-bit A/D Converter module uses up to
43 registers for its operation. All registers are mapped
in the data memory space.
22.1.1
CONTROL REGISTERS
Depending on the specific device, the module has up to
eleven control and status registers:
AD1CON1: A/D Control Register 1
AD1CON2: A/D Control Register 2
AD1CON3: A/D Control Register 3
AD1CON5: A/D Control Register 5
AD1CHS: A/D Sample Select Register
AD1CHITH and AD1CHITL: A/D Scan Compare
Hit Registers
AD1CSSL and AD1CSSH: A/D Input Scan Select
Registers
AD1CTMENH and AD1CTMENL: CTMU Enable
Registers
The AD1CON1, AD1CON2 and AD1CON3 registers
and
control the overall operation of the A/D module. This
includes enabling the module, configuring the
conversion clock and voltage reference sources,
selecting the sampling and conversion triggers, and
manually controlling the sample/convert sequences.
controls features of the Threshold Detect operation,
including its function in power-saving modes.
channels to be connected to the S/H amplifier. It also
allows the choice of input multiplexers and the
selection of a reference source for differential
sampling.
The
AD1CHITH
and
AD1CHITL
registers
registers used with Threshold Detect operations. The
status of individual bits, or bit pairs in some cases,
indicate if a match condition has occurred. AD1CHITL
is always implemented, whereas AD1CHITH may not
be implemented in devices with 16 or fewer channels.
The
AD1CSSH/L
registers
and
sequential scanning.
CTMU during conversions. Selecting a particular
channel allows the A/D Converter to control the CTMU
(particularly, its current source) and read its data
through that channel. AD1CTMENL is always
implemented, whereas AD1CTMENH may not be
implemented in devices with 16 or fewer channels.
22.1.2
A/D RESULT BUFFERS
The module incorporates a multi-word, dual port RAM,
called ADC1BUF. The buffer is composed of at least
the same number of word locations as there are
external analog channels for a particular device, with a
maximum number of 32. The number of buffer
addresses is always even. Each of the locations is
mapped into the data memory space and is separately
addressable. The buffer locations are referred to as
ADC1BUF0 through ADC1BUFn (up to 31).
The A/D result buffers are both readable and writable.
When the module is active (AD1CON<15> = 1), the
buffers are read-only, and store the results of A/D
conversions.
When
the
module
is
inactive
(AD1CON<15> = 0), the buffers are both readable and
writable. In this state, writing to a buffer location
programs a conversion threshold for Threshold Detect
operations.
Buffer contents are not cleared when the module is
deactivated with the ADON bit (AD1CON1<15>).
Conversion results and any programmed threshold
values are maintained when ADON is set or cleared.