PIC18F44K20-E/MV Microchip Technology, PIC18F44K20-E/MV Datasheet - Page 242

• Manufacturer Part Number: PIC18F44K20-E/MV
• Description: 16KB, Flash, 768bytes-RAM, 36I/O, 8-bit Family,nanowatt XLP 40 UQFN 5x5x0.5mm TU
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F44K20-E/MV

• Processor Series: PIC18
• Core: PIC18F
• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 8 KB
• Data Ram Size: 512 B
• Interface Type: I2C, SPI, SCI, USB, MSSP, RJ11
• Maximum Clock Frequency: 64 MHz
• Number Of Programmable I/os: 35
• Number Of Timers: 4
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: UQFN-40
• Development Tools By Supplier: MPLAB Integrated Development Environment
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 125 C
• Supply Current (max): 30 uA
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 35
• Eeprom Size: 256 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Lead Free Status / Rohs Status: Details

PIC18F2XK20/4XK20
18.1.2
The Asynchronous mode would typically be used in
RS-232 systems. The receiver block diagram is shown
in Figure 18-2. The data is received on the RX/DT pin
and drives the data recovery block. The data recovery
block is actually a high-speed shifter operating at 16
times the baud rate, whereas the serial Receive Shift
Register (RSR) operates at the bit rate. When all 8 or 9
bits of the character have been shifted in, they are
immediately
First-In-First-Out (FIFO) memory. The FIFO buffering
allows reception of two complete characters and the
start of a third character before software must start
servicing the EUSART receiver. The FIFO and RSR
registers are not directly accessible by software.
Access to the received data is via the RCREG register.
18.1.2.1
The EUSART receiver is enabled for asynchronous
operation by configuring the following three control bits:
• CREN = 1
• SYNC = 0
• SPEN = 1
All other EUSART control bits are assumed to be in
their default state.
Setting the CREN bit of the RCSTA register enables the
receiver circuitry of the EUSART. Clearing the SYNC bit
of the TXSTA register configures the EUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the EUSART. The RX/DT I/O
pin must be configured as an input by setting the
corresponding TRIS control bit. If the RX/DT pin is
shared with an analog peripheral the analog I/O function
must be disabled by clearing the corresponding ANSEL
bit.
DS41303G-page 242
EUSART ASYNCHRONOUS
RECEIVER
Enabling the Receiver
transferred
to
a
two
character
18.1.2.2
The receiver data recovery circuit initiates character
reception on the falling edge of the first bit. The first bit,
also known as the Start bit, is always a zero. The data
recovery circuit counts one-half bit time to the center of
the Start bit and verifies that the bit is still a zero. If it is
not a zero then the data recovery circuit aborts
character reception, without generating an error, and
resumes looking for the falling edge of the Start bit. If
the Start bit zero verification succeeds then the data
recovery circuit counts a full bit time to the center of the
next bit. The bit is then sampled by a majority detect
circuit and the resulting ‘0’ or ‘1’ is shifted into the RSR.
This repeats until all data bits have been sampled and
shifted into the RSR. One final bit time is measured and
the level sampled. This is the Stop bit, which is always
a ‘1’. If the data recovery circuit samples a ‘0’ in the
Stop bit position then a framing error is set for this
character, otherwise the framing error is cleared for this
character. See Section 18.1.2.5 “Receive Framing
Error” for more information on framing errors.
Immediately after all data bits and the Stop bit have
been received, the character in the RSR is transferred
to the EUSART receive FIFO and the RCIF interrupt
flag bit of the PIR1 register is set. The top character in
the FIFO is transferred out of the FIFO by reading the
RCREG register.
18.1.2.3
The polarity of the receive data can be controlled with
the DTRXP bit of the BAUDCON register. The default
state of this bit is ‘0’ which selects high true receive idle
and data bits. Setting the DTRXP bit to ‘1’ will invert the
receive data resulting in low true idle and data bits. The
DTRXP bit controls receive data polarity only in Asyn-
chronous mode. In synchronous mode the DTRXP bit
has a different function.
Note:
If the receive FIFO is overrun, no additional
characters will be received until the overrun
condition is cleared. See Section 18.1.2.6
“Receive Overrun Error” for more
information on overrun errors.
Receiving Data
Receive Data Polarity
 2010 Microchip Technology Inc.