PIC16F877-04E/PT Microchip Technology, PIC16F877-04E/PT Datasheet - Page 398

• Manufacturer Part Number: PIC16F877-04E/PT
• Description: IC MCU FLASH 8KX14 EE 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-04E/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Size: 14KB (8K x 14)
• Program Memory Type: FLASH
• 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 ~ 125°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: PIC16F87704E/PT

PICmicro MID-RANGE MCU FAMILY
21.11
21.12
21.13
DS31021A-page 21-14
Use of the CCP Trigger
Connection Considerations
Transfer Function
An A/D conversion may be started by the “special event trigger” of a CCP module. This requires
that the CCPxM3:CCPxM0 bits (CCPxCON<3:0>) be programmed as 1011 and that the A/D
module is enabled (ADON bit is set). When the trigger occurs, the GO/DONE bit will be set, start-
ing the A/D conversion, and the Timer1 counter will be reset to zero. Timer1 is reset to automat-
ically repeat the A/D acquisition period with minimal software overhead (moving the ADRES to
the desired location). The appropriate analog input channel must be selected and the minimum
acquisition done before the “special event trigger” sets the GO/DONE bit (starts a conversion).
If the A/D module is not enabled (ADON is cleared), then the “special event trigger” will be
ignored by the A/D module, but will still reset the Timer1 counter.
If the input voltage exceeds the rail values (V
of the conversion is out of specification.
An external RC filter can sometimes be added for anti-aliasing of the input signal. The R compo-
nent should be selected to ensure that the total source impedance is kept under the 10 k rec-
ommended specification. Any external components connected (via hi-impedance) to an analog
input pin (capacitor, zener diode, etc.) should have very little leakage current at the pin.
The ideal transfer function of the A/D converter is as follows: the first transition occurs when the
analog input voltage (V
Figure 21-6: A/D Transfer Function
AIN
) is 1 LSb (or Analog V
FEh
FFh
04h
03h
02h
01h
00h
Analog input voltage
SS
or V
REF
DD
/ 256)
) by greater than 0.3V, then the accuracy
(Figure
1997 Microchip Technology Inc.
21-6).