PIC16C554-20I/P Microchip Technology, PIC16C554-20I/P Datasheet - Page 30

• Manufacturer Part Number: PIC16C554-20I/P
• Description: IC MCU OTP 512X14 18DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C554-20I/P

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: POR, WDT
• Number Of I /o: 13
• Program Memory Size: 896B (512 x 14)
• Program Memory Type: OTP
• Ram Size: 80 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 18-DIP (0.300", 7.62mm)
• Processor Series: PIC16C
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 80 B
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 13
• Number Of Timers: 8
• Operating Supply Voltage: 2.5 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: ICE2000
• Minimum Operating Temperature: - 40 C
• Data Rom Size: 80 B
• Height: 3.3 mm
• Length: 22.86 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Width: 6.35 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Details

PIC16C55X
5.4
5.4.1
Any instruction which writes, operates internally as a
read followed by a write operation. The BCF and BSF
instructions, for example, read the register into the
CPU, execute the bit operation and write the result
back to the register. Caution must be used when these
instructions are applied to a port with both inputs and
outputs defined. For example, a BSF operation on bit5
of PORTB will cause all eight bits of PORTB to be read
into the CPU. Then the BSF operation takes place on
bit5 and PORTB is written to the output latches. If
another bit of PORTB is used as a bi-directional I/O pin
(e.g., bit 0) and it is defined as an input at this time, the
input signal present on the pin itself would be read into
the CPU and re-written to the data latch of this
particular pin, overwriting the previous content. As long
as the pin stays in the Input mode, no problem occurs.
However, if bit 0 is switched into Output mode later on,
the content of the data latch may now be unknown.
DS40143D-page 28
I/O Programming Considerations
BI-DIRECTIONAL I/O PORTS
Preliminary
Reading the port register, reads the values of the port
pins. Writing to the port register writes the value to the
port latch. When using read-modify-write instructions
(ex. BCF, BSF, etc.) on a port, the value of the port pins
is read, the desired operation is done to this value, and
this value is then written to the port latch.
Example 5-1 shows the effect of two sequential read-
modify-write instructions (ex., BCF,BSF, etc.) on an
I/O port.
A pin actively outputting a low or high should not be
driven from external devices at the same time in order
to change the level on this pin (“wired-or”, “wired-and”).
The resulting high output currents may damage
the chip.
 2002 Microchip Technology Inc.