PIC16F74-I/PTG Microchip Technology, PIC16F74-I/PTG Datasheet - Page 192

• Manufacturer Part Number: PIC16F74-I/PTG
• Description: IC MCU FLASH 4KX14 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F74-I/PTG

• 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
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: FLASH
• Ram Size: 192 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x8b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

PICmicro MID-RANGE MCU FAMILY
12.12
DS31012A-page 12-12
Design Tips
Question 1:
Answer 1:
There are a few reasons that this could occur
1.
2.
You should never write to Timer1, where that could cause the loss of time. In most cases
that means you should not write to the TMR1L register, but if the conditions are ok, you
may write to the TMR1H register. Normally you write to the TMR1H register if you want the
Timer1 overflow interrupt to be sooner then the full 16-bit time-out.
You should ensure the your layout uses good PCB layout techniques so that noise does
not couple onto the Timer1 oscillator lines.
Timer1 does not seem to be keeping accurate time.
1997 Microchip Technology Inc.