PIC16F872-E/SS Microchip Technology, PIC16F872-E/SS Datasheet - Page 407

• Manufacturer Part Number: PIC16F872-E/SS
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,SSOP,28PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F872-E/SS

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 64 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-SSOP
• Package: 28SSOP
• Device Core: PIC
• Family Name: PIC16
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 22
• Interface Type: I2C/SPI
• On-chip Adc: 5-chx10-bit
• Number Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1997 Microchip Technology Inc.
Section 22. Basic 8-bit A/D Converter
The ADRES register contains the result of the A/D conversion. When the A/D conversion is com-
plete, the result is loaded into the ADRES register, the GO/DONE bit (ADCON0<2>) is cleared,
and A/D interrupt flag bit ADIF is set. The block diagram of the A/D module is shown in
Figure
After the A/D module has been configured as desired, the selected channel must be acquired
before the conversion is started. The analog input channels must have their corresponding TRIS
bits selected as an input. To determine sample time, see Subsection
Requirements”
following steps should be followed for doing an A/D conversion:
1.
2.
3.
4.
5.
6.
7.
Figure 22-2
time that the A/D module’s holding capacitor is connected to the external voltage level. Then
there is the conversion time of 10 T
two times is the sampling time. There is a minimum acquisition time to ensure that the holding
capacitor is charged to a level that will give the desired accuracy for the A/D conversion.
Figure 22-2:
Configure the A/D module:
• Configure analog pins / voltage reference / and digital I/O (ADCON1)
• Select A/D input channel (ADCON0)
• Select A/D conversion clock (ADCON0)
• Turn on A/D module (ADCON0)
Configure A/D interrupt (if desired):
• Clear the ADIF bit
• Set the ADIE bit
• Set the GIE bit
Wait the required acquisition time.
Start conversion:
• Set the GO/DONE bit (ADCON0)
Wait for A/D conversion to complete, by either:
• Polling for the GO/DONE bit to be cleared
OR
• Waiting for the A/D interrupt
Read A/D Result register (ADRES), clear the ADIF bit, if required.
For next conversion, go to step 1 or step 2 as required. The A/D conversion time per bit is
defined as T
When A/D holding capacitor start to charge.
After A/D conversion, or new A/D channel is selected
22-1.
Acquisition Time
shows the conversion sequence, and the terms that are used. Acquisition time is the
A/D Conversion Sequence
AD
After this acquisition time has elapsed the A/D conversion can be started. The
. A minimum wait of 2T
A/D Sample Time
When A/D conversion is started (setting the GO bit)
A/D Conversion Time
AD
, which is started when the GO bit is set. The sum of these
AD
is required before next acquisition starts.
A/D conversion complete,
result is loaded in ADRES register.
Holding capacitor begins acquiring
voltage level on selected channel
ADIF bit is set
22.3 “A/D Acquisition
DS31022A-page 22-5
22