PIC16F877A-I/P Microchip Technology, PIC16F877A-I/P Datasheet - Page 427

• Manufacturer Part Number: PIC16F877A-I/P
• Description: IC MCU FLASH 8KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877A-I/P

• Program Memory Type: FLASH
• Program Memory Size: 14KB (8K x 14)
• Package / Case: 40-DIP (0.600", 15.24mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 368 B
• Interface Type: CCP/I2C/MSSP/SPI/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 33
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163022, DV164120
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: PIC16F877AI/P

23.3
1997 Microchip Technology Inc.
Operation
The ADRESH:ADRESL registers contains the 10-bit result of the A/D conversion. When the A/D
conversion is complete, the result is loaded into this A/D result register pair, the GO/DONE bit
(ADCON0<2>) is cleared, and A/D interrupt flag bit, ADIF, is set. The block diagrams of the A/D
module are shown in
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 inputs. 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 23-2
time that the A/D module’s holding capacitor is connected to the external voltage level. Then
there is the conversion time of 12 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 23-2: A/D Conversion Sequence
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 ADIF bit to be set
OR
• Waiting for the A/D interrupt
Read A/D Result register pair (ADRESH:ADRESL), clear the ADIF bit, if required.
For next conversion, go to step 1 or step 2 as required.
When A/D holding capacitor starts to charge.
After A/D conversion, or when new A/D channel is selected
Acquisition Time
Section 23. 10-bit A/D Converter
shows the conversion sequence, and the terms that are used. Acquisition time is the
After this acquisition time has elapsed the A/D conversion can be started. The
Figure
A/D Sample Time
Preliminary
When A/D conversion is started (setting the GO bit)
23-1.
A/D Conversion Time
AD
, which is started when the GO bit is set. The sum of these
A/D conversion complete,
result is loaded in ADRES register.
Holding capacitor begins acquiring
voltage level on selected channel
ADIF bit is set
23.4 “A/D Acquisition
DS31023A-page 23-5
23