PIC16F87-I/SS Microchip Technology, PIC16F87-I/SS Datasheet - Page 142

• Manufacturer Part Number: PIC16F87-I/SS
• Description: IC MCU FLASH 4KX14 EEPROM 20SSOP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F87-I/SS

• Program Memory Type: FLASH
• Program Memory Size: 7KB (4K x 14)
• Package / Case: 20-SSOP
• 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: 16
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 368 B
• Interface Type: SSP/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• 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, DM163014
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT20SS-1 - SOCKET TRANSITION 18DIP 20SSOPAC164307 - MODULE SKT FOR PM3 28SSOP
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
9.1
DS31009A-page 9-2
Introduction
General purpose I/O pins can be considered the simplest of peripherals. They allow the
PICmicro™ to monitor and control other devices. To add flexibility and functionality to a device,
some pins are multiplexed with an alternate function(s). These functions depend on which
peripheral features are on the device. In general, when a peripheral is functioning, that pin may
not be used as a general purpose I/O pin.
For most ports, the I/O pin’s direction (input or output) is controlled by the data direction register,
called the TRIS register. TRIS<x> controls the direction of PORT<x>. A ‘1’ in the TRIS bit corre-
sponds to that pin being an input, while a ‘0’ corresponds to that pin being an output. An easy
way to remember is that a ‘1’ looks like an I (input) and a ‘0’ looks like an O (output).
The PORT register is the latch for the data to be output. When the PORT is read, the device reads
the levels present on the I/O pins (not the latch). This means that care should be taken with
read-modify-write commands on the ports and changing the direction of a pin from an input to an
output.
Figure 9-1
be multiplexed onto the I/O pin. Reading the PORT register reads the status of the pins whereas
writing to it will write to the port latch. All write operations (such as BSF and BCF instructions) are
read-modify-write operations. Therefore a write to a port implies that the port pins are read, this
value is modified, and then written to the port data latch.
Figure 9-1: Typical I/O Port
WR PORT
WR TRIS
RD PORT
Data bus
Note: I/O pin has protection diodes to V
shows a typical I/O port. This does not take into account peripheral functions that may
Data Latch
TRIS Latch
D
CK
D
CK
RD TRIS
Q
Q
Q
Q
DD
and V
Q
SS
EN
.
D
V
V
P
N
DD
SS
1997 Microchip Technology Inc.
Trigger
Schmitt
TTL or
I/O pin