PIC16F84-04I/SO Microchip Technology, PIC16F84-04I/SO Datasheet - Page 25
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PIC16F84-04I/SO
Manufacturer Part Number
PIC16F84-04I/SO
Description
IC MCU FLASH 1KX14 EE 18SOIC
Manufacturer
Microchip Technology
Series
PIC® 16Fr
Datasheets
1.PIC16F688T-ISL.pdf
(688 pages)
2.PIC16LF84A-04P.pdf
(125 pages)
3.PIC16LF84A-04P.pdf
(4 pages)
Specifications of PIC16F84-04I/SO
Core Size
8-Bit
Program Memory Size
1.75KB (1K x 14)
Core Processor
PIC
Speed
4MHz
Peripherals
POR, WDT
Number Of I /o
13
Program Memory Type
FLASH
Eeprom Size
64 x 8
Ram Size
68 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 6 V
Oscillator Type
External
Operating Temperature
-40°C ~ 85°C
Package / Case
18-SOIC (7.5mm Width)
Controller Family/series
PIC16F
No. Of I/o's
13
Eeprom Memory Size
64Byte
Ram Memory Size
68Byte
Cpu Speed
4MHz
No. Of Timers
1
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With
XLT18SO-1 - SOCKET TRANSITION 18SOIC 300MIL309-1075 - ADAPTER 18-SOIC TO 18-SOIC309-1011 - ADAPTER 18-SOIC TO 18-DIP309-1010 - ADAPTER 18-SOIC TO 18-DIPAC164010 - MODULE SKT PROMATEII DIP/SOIC
Data Converters
-
Connectivity
-
Lead Free Status / RoHS Status
Lead free / RoHS Compliant, Lead free / RoHS Compliant
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
(i.e., 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 rewritten 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 is 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
(i.e., 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.
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 current may damage the chip.
FIGURE 5-5:
1998 Microchip Technology Inc.
Instruction
Instruction
RB7:RB0
executed
fetched
I/O Programming Considerations
BI-DIRECTIONAL I/O PORTS
PC
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
MOVWF PORTB
SUCCESSIVE I/O OPERATION
write to
PORTB
PC
MOVF PORTB,W
MOVWF PORTB
write to
PORTB
PC + 1
T
MOVF PORTB,W
PD
Port pin
sampled here
NOP
PC + 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 5-5). 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 that the pin voltage stabilizes (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.
Example 5-1 shows the effect of two sequential
read-modify-write instructions (e.g., BCF, BSF, etc.) on
an I/O port.
EXAMPLE 5-1:
;Initial PORT settings: PORTB<7:4> Inputs
;
;PORTB<7:6> have external pull-ups and are
;not connected to other circuitry
;
;
;
;
;Note that the user may have expected the
;pin values to be 00pp ppp. The 2nd BCF
;caused RB7 to be latched as the pin value
;(high).
BCF PORTB, 7
BCF PORTB, 6
BSF STATUS, RP0
BCF TRISB, 7
BCF TRISB, 6
PC + 3
NOP
NOP
SUCCESSIVE OPERATIONS ON I/O
PORTS
Note:
This example shows a write to PORTB
followed by a read from PORTB.
Note that:
data setup time = (0.25T
where T
Therefore, at higher clock frequencies,
a write followed by a read may be prob-
lematic.
READ-MODIFY-WRITE
INSTRUCTIONS ON AN
I/O PORT
; 01pp ppp
; 10pp ppp
;
; 10pp ppp
; 10pp ppp
T
PORT latch
----------
CY
PD
PIC16F8X
PORTB<3:0> Outputs
= instruction cycle
= propagation delay
DS30430C-page 25
PORT pins
---------
11pp ppp
11pp ppp
11pp ppp
10pp ppp
CY
- T
PD
)