PIC16F747-E/ML Microchip Technology, PIC16F747-E/ML Datasheet - Page 58

• Manufacturer Part Number: PIC16F747-E/ML
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,LLCC,44PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F747-E/ML

• Rohs Compliant: YES
• 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: 36
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: FLASH
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 44-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: I3DBF777 - BOARD DAUGHTER ICEPIC3
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC16F7X7
5.2
PORTB is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISB. Setting a
TRISB bit (= 1) will make the corresponding PORTB
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISB bit (= 0)
will make the corresponding PORTB pin an output (i.e.,
put the contents of the output latch on the selected pin).
Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is
performed by clearing bit RBPU (OPTION_REG<7>).
The weak pull-up is automatically turned off when the
port pin is configured as an output. The pull-ups are
disabled on a Power-on Reset.
PORTB pins are multiplexed with analog inputs. The
operation of each pin is selected by clearing/setting the
appropriate control bits in the ADCON1 register.
Four of the PORTB pins (RB7:RB4) have an interrupt-
on-change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt-
on-change comparison). The input pins (of RB7:RB4)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB7:RB4
are ORed together to generate the RB port change
interrupt with flag bit, RBIF (INTCON<0>).
This interrupt can wake the device from Sleep. The
user, in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a)
b)
A mismatch condition will continue to set flag bit RBIF.
Reading PORTB will end the mismatch condition and
allow flag bit RBIF to be cleared.
DS30498C-page 56
Note:
Any read or write of PORTB. This will end the
mismatch condition.
Clear flag bit RBIF.
PORTB and the TRISB Register
On a Power-on Reset, these pins are
configured as analog inputs and read as
‘0’.
The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.
This interrupt on mismatch feature, together with soft-
ware configureable pull-ups on these four pins, allow
easy interface to a keypad and make it possible for
wake-up on key depression. Refer to the Application
Note AN552 “Implementing Wake-up on Key Stroke”
(DS00552).
RB0/INT is an external interrupt input pin and is
configured using the INTEDG bit (OPTION_REG<6>).
RB0/INT is discussed in detail in Section 15.15.1 “INT
Interrupt”.
PORTB is multiplexed with several peripheral functions
(see Table 5-3). PORTB pins have Schmitt Trigger
input buffers.
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTB pin. Some
peripherals override the TRIS bit to make a pin an out-
put, while other peripherals override the TRIS bit to
make a pin an input. Since the TRIS bit override is in
effect while the peripheral is enabled, read-modify-
write instructions (BSF, BCF, XORWF) with TRISB as
destination should be avoided. The user should refer to
the corresponding peripheral section for the correct
TRIS bit settings.
 2004 Microchip Technology Inc.