PIC16C622A-20/SO Microchip Technology, PIC16C622A-20/SO Datasheet - Page 32

• Manufacturer Part Number: PIC16C622A-20/SO
• Description: IC MCU OTP 2KX14 COMP 18SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16C622A-20/SO

• Program Memory Type: OTP
• Program Memory Size: 3.5KB (2K x 14)
• Package / Case: 18-SOIC (7.5mm Width)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: Brown-out Detect/Reset, POR, WDT
• Number Of I /o: 13
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.5 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Processor Series: PIC16C
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 13
• Number Of Timers: 1
• Operating Supply Voltage: 3 V to 5.5 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: ICE2000, DM163022
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT18SO-1 - SOCKET TRANSITION 18SOIC 300MILISPICR1 - ADAPTER IN-CIRCUIT PROGRAMMING309-1011 - ADAPTER 18-SOIC TO 18-DIP309-1010 - ADAPTER 18-SOIC TO 18-DIPAC164010 - MODULE SKT PROMATEII DIP/SOIC
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC16C62X
5.3
5.3.1
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., bit0) 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 bit0 is switched into Output mode later on,
the content of the data latch may now be unknown.
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 5-2 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.
FIGURE 5-7:
DS30235J-page 30
Instruction
Instruction
RB<7:0>
RB <7:0>
fetched
fetched
PC
PC
I/O Programming Considerations
BI-DIRECTIONAL I/O PORTS
Q1
Q1
MOVWF PORTB
MOVWF, PORTB
Q2
Q2
Write to
Write to
PORTB
PORTB
PC
PC
SUCCESSIVE I/O OPERATION
Q3
Q3 Q4
Q4
Q1
Q1
MOVF PORTB, W
MOVF, PORTB, W
Read PORTB
Read PORTB
MOVWF
MOVWF
Execute
Execute
PORTB
PORTB
Q2
Q2 Q3
PC + 1
PC+1
T
T
Q3
PD
PD
Q4
Q4 Q1
Q1
Port pin
sampled here
Port pin
sampled here
PORTB, W
Q2
Q2
PORTB, W
PC + 2
PC+2
Execute
Execute
NOP
MOVF
NOP
MOVF
Q3 Q4
Q3
Q4
EXAMPLE 5-2:
5.3.2
The actual write to an I/O port happens at the end of an
instruction cycle, whereas for reading, the data must be
valid at the beginning of the instruction cycle (Figure 5-7).
Therefore, care must be exercised if a write followed by a
read operation is carried out on the same I/O port. The
sequence of instructions should be such to allow the pin
voltage to stabilize (load dependent) before the next
instruction which causes that file to be read into the CPU
is executed. Otherwise, the previous state of that pin may
be read into the CPU rather than the new state. When in
doubt, it is better to separate these instructions with a NOP
or another instruction not accessing this I/O port.
;
;
;
;
;
;
;
;
;
; Note that the user may have expected the pin
; values to be 00pp pppp. The 2nd BCF caused
; RB7 to be latched as the pin value (High).
Initial PORT settings:
PORTB<7:6> have external pull-up and are not
connected to other circuitry
Q1
Q1
BCF PORTB, 7
BCF PORTB, 6
BSF STATUS,RP0
BCF TRISB, 7
BCF TRISB, 6
Execute
Execute
Q2
Q2
PC + 3
PC+3
NOP
NOP
NOP
NOP
SUCCESSIVE OPERATIONS ON I/O
PORTS
Q3
Q3 Q4
Q4
READ-MODIFY-WRITE
INSTRUCTIONS ON AN I/O
PORT
Note:
This example shows write to PORTB
followed by a read from PORTB.
Note that:
Therefore, at higher clock frequen-
cies, a write followed by a read may
be problematic.
 2003 Microchip Technology Inc.
data setup time = (0.25 T
where T
TPD = propagation delay of Q1
cycle to output valid.
; 01pp pppp
; 10pp pppp
;
; 10pp pppp
; 10pp pppp
PORTB<7:4> Inputs
PORTB<3:0> Outputs
PORT latch
----------
CY
= instruction cycle and
PORT pins
---------
-
11pp pppp
11pp pppp
11pp pppp
10pp pppp
CY
- T
PD
)