PIC16HV540-04I/SS Microchip Technology, PIC16HV540-04I/SS Datasheet - Page 22

• Manufacturer Part Number: PIC16HV540-04I/SS
• Description: IC MCU OTP 512X12 20SSOP
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16HV540-04I/SS

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: Brown-out Detect/Reset, POR, WDT
• Number Of I /o: 12
• Program Memory Size: 768B (512 x 12)
• Program Memory Type: OTP
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 3.5 V ~ 15 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-SSOP
• Processor Series: PIC16H
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 25 B
• Maximum Clock Frequency: 4 MHz
• Number Of Programmable I/os: 12
• Number Of Timers: 8
• Operating Supply Voltage: 3.5 V to 15 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: 309-1016 - ADAPTER 20-SSOP TO 18-DIP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Details

PIC16HV540
TABLE 5-1:
5.5
5.5.1
Some instructions operate internally as read followed
by write operations. The BCF and BSF instructions, for
example, read the entire port into the CPU, execute the
bit operation and re-write the result. Caution must be
used when these instructions are applied to a port
where one or more pins are used as input/outputs. For
example, a BSF operation on bit5 of PORTB will cause
all eight bits of PORTB to be read into the CPU, bit5 to
be set and the PORTB value to be written to the output
latches. If another bit of PORTB is used as a bi-direc-
tional I/O pin (say 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 may now be
unknown.
Example 5-1 shows the effect of two sequential read-
modify-write instructions (e.g., BCF, BSF, etc.) on an I/
O port.
A pin actively outputting a high or a low 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.
DS40197B-page 22
N/A
05h
06h
03h
N/A
Legend:
Address
TRIS
PORTA
PORTB
STATUS
OPTION2
I/O Programming Considerations
BI-DIRECTIONAL I/O PORTS
Shaded boxes = unimplemented, read as ‘0’, —= unimplemented, read as '0', x = unknown, u = unchanged.
Name
I/O control registers (TRISA, TRISB)
PCWUF
SUMMARY OF PORT REGISTERS
Bit 7
RB7
—
—
Bit 6
RB6
PA1
—
—
PCWU
Bit 5
RB5
PA0
—
SWDTEN
Bit 4
RB4
TO
—
Bit 3
RA3
RB3
PD
RL
Preliminary
Bit 2
RA2
RB2
SL
Z
BODL
Bit 1
RA1
RB1
DC
EXAMPLE 5-1:
;Initial PORT Settings
; PORTB<7:4> Inputs
; PORTB<3:0> Outputs
;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 pppp. The 2nd BCF caused
;RB7 to be latched as the pin value (High).
5.5.2
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
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.
BCF
BCF
MOVLW 03Fh
TRIS
BODEN
Bit 0
RA0
RB0
C
SUCCESSIVE OPERATIONS ON I/O
PORTS
PORTB, 7
PORTB, 6
PORTB
1111 1111
---- xxxx
xxxx xxxx
100x xxxx
--11 1111
Power-On
Value on
Reset
READ-MODIFY-WRITE
INSTRUCTIONS ON AN
I/O PORT
WDT Reset
1111 1111
---- uuuu
uuuu uuuu
100q quuu
--uu uuuu
MCLR and
;01pp pppp
;10pp pppp
;
;10pp pppp
Value on
PORT latch
----------
2000 Microchip Technology Inc.
Wake-up on
Pin Change
1111 1111
---- uuuu
uuuu uuuu
000u uuuu
--uu uuuu
Value on
PORT pins
11pp pppp
11pp pppp
10pp pppp
----------
1111 1111
---- xxxx
xxxx xxxx
x00x xxxx
--xx xxxx
Brown-Out
Value on
Reset