PIC16F877-20I/PT Microchip Technology, PIC16F877-20I/PT Datasheet - Page 138

• Manufacturer Part Number: PIC16F877-20I/PT
• Description: IC MCU FLASH 8KX14 EE 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-20I/PT

• Program Memory Type: FLASH
• Program Memory Size: 14KB (8K x 14)
• Package / Case: 44-TQFP, 44-VQFP
• 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: MSSP/PSP/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: SMD/SMT
• 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: XLT44PT3 - SOCKET TRAN ICE 44MQFP/TQFPAC164305 - MODULE SKT FOR PM3 44TQFP444-1001 - DEMO BOARD FOR PICMICRO MCUAC164020 - MODULE SKT PROMATEII 44TQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
8.7
DS31008A-page 8-16
Design Tips
Question 1:
Answer 1:
Assuming that the algorithm is correct and that interrupts are enabled during the algorithm,
ensure that are registers that are used by the algorithm and by the interrupt service routine are
saved and restored. If not some registers may be corrupted by the execution of the ISR.
Question 2:
Answer 2:
If interrupts are being used, ensure that the interrupt flag is cleared after servicing that interrupt
(but before executing the RETFIE instruction). If the interrupt flag remains set when the RETFIE
instruction is executed, program execution immediately returns to the interrupt vector, since there
is an outstanding enabled interrupt.
An algorithm does not give the correct results.
My system seems to lock up.
1997 Microchip Technology Inc.