PIC16F707 Datasheet, PDF (141/284 Pages) Microchip Technology – 40/44-Pin, Flash Microcontrollers with nanoWatt XLP and mTouch™ Technology

PIC16F707/PIC16LF707
TABLE 18-1: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
INTCON
PIE1
PIR1
RCSTA
SPBRG
TRISC
TXREG
TXSTA
Legend:
GIE
PEIE TMR0IE INTE
RBIE TMR0IF INTF
RBIF 0000 000x 0000 000x
TMR1GIE ADIE
RCIE
TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000
TMR1GIF ADIF
RCIF
TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000
SPEN
RX9
SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
BRG7 BRG6 BRG5 BRG4 BRG3 BRG2 BRG1 BRG0 0000 0000 0000 0000
TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111
AUSART Transmit Data Register
0000 0000 0000 0000
CSRC
TX9
TXEN SYNC
—
BRGH TRMT TX9D 0000 -010 0000 -010
x = unknown, - = unimplemented read as ‘0’. Shaded cells are not used for asynchronous transmission.
18.1.2 AUSART ASYNCHRONOUS
RECEIVER
The Asynchronous mode is typically 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 transferred to a two character 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
AUSART 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 Enabling the Receiver
The AUSART receiver is enabled for asynchronous
operation by configuring the following three control bits:
• CREN = 1
• SYNC = 0
• SPEN = 1
All other AUSART control bits are assumed to be in
their default state.
Setting the CREN bit of the RCSTA register enables the
receiver circuitry of the AUSART. Clearing the SYNC bit
of the TXSTA register configures the AUSART for
asynchronous operation. Setting the SPEN bit of the
RCSTA register enables the AUSART and
automatically configures the RX/DT I/O pin as an input.
Note 1: When the SPEN bit is set, the TX/CK I/O
pin is automatically configured as an out-
put, regardless of the state of the corre-
sponding TRIS bit and whether or not the
AUSART transmitter is enabled. The
PORT latch is disconnected from the out-
put driver so it is not possible to use the
TX/CK pin as a general purpose output.
2: The corresponding ANSEL bit must be
cleared for the RX/DT port pin to ensure
proper AUSART functionality.
 2010 Microchip Technology Inc.
Preliminary
DS41418A-page 141