DSPIC33FJ12MC02ESS datasheet(201/284 Pages) MICROCHIP

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Preliminary

DS70265B-page 199

dsPIC33FJ12MC201/202

19.0 10-BIT/12-BIT ANALOG-TO-

DIGITAL CONVERTER (ADC)

The dsPIC33FJ12MC201/202 devices have up to 6

ADC module input channels.

The AD12B bit (ADxCON1<10>) allows each of the

ADC modules to be configured as either a 10-bit, 4-

sample-and-hold ADC (default configuration) or a 12-

bit, 1 sample-and-hold ADC.

19.1

Key Features

The 10-bit ADC configuration has the following key

features:

• Successive Approximation (SAR) conversion

• Conversion speeds of up to 1.1 Msps

• Up to 6 analog input pins

• External voltage reference input pins

• Simultaneous sampling of up to four analog input

pins

• Automatic Channel Scan mode

• Selectable conversion trigger source

• Selectable Buffer Fill modes

• Four result alignment options (signed/unsigned,

fractional/integer)

• Operation during CPU Sleep and Idle modes

• 16-word conversion result buffer

The 12-bit ADC configuration supports all the above

features, except:

• In the 12-bit configuration, conversion speeds of

up to 500 ksps are supported

• There is only 1 sample-and-hold amplifier in the

12-bit configuration, so simultaneous sampling of

multiple channels is not supported.

Depending on the particular device pinout, the ADC

can have up to 6 analog input pins, designated AN0

through AN5. In addition, there are two analog input

pins for external voltage reference connections. These

voltage reference inputs can be shared with other

analog input pins.

The actual number of analog input pins and external

voltage reference input configuration will depend on the

specific device.

A block diagram of the ADC is shown in Figure 19-1.

19.2

ADC Initialization

To configure the ADC module:

Select

port

pins

analog

inputs

(ADxPCFGH<15:0> or ADxPCFGL<15:0>).

Select voltage reference source to match

expected

range

analog

inputs

(ADxCON2<15:13>).

Select the analog conversion clock to match the

desired data rate with the processor clock

(ADxCON3<5:0>).

Determine how many sample-and-hold chan-

nels will be used (ADxCON2<9:8> and

ADxPCFGH<15:0> or ADxPCFGL<15:0>).

Select

the

appropriate

sample/conversion

sequence

(ADxCON1<7:5>

and

ADxCON3<12:8>).

Select the way conversion results are presented

in the buffer (ADxCON1<9:8>).

Turn on the ADC module (ADxCON1<15>).

Configure ADC interrupt (if required):

a) Clear the ADxIF bit.

b) Select the ADC interrupt priority.

Note:

This data sheet summarizes the features

of the dsPIC33FJ12MC201/202 devices.

It is not intended to be a comprehensive

reference source. To complement the

information in this data sheet, refer to the

“dsPIC33F Family Reference Manual”.

Please see the Microchip web site

(www.microchip.com)

for

the

latest

dsPIC33F Family Reference Manual

chapters.

Note:

The ADC module must be disabled before

the AD12B bit can be modified.

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