PIC16F883 Microchip Technology Inc., PIC16F883 Datasheet - Page 160

• Manufacturer Part Number: PIC16F883
• Description: 28/40/44-pin Flash-based, 8-bit Cmos Microcontrollers With Nanowatt Technology
• Manufacturer: Microchip Technology Inc.

PIC16F822/883/884/886/887
12.2
The factory calibrates the internal oscillator block out-
put (INTOSC). However, the INTOSC frequency may
drift as V
affects the asynchronous baud rate. Two methods may
be used to adjust the baud rate clock, but both require
a reference clock source of some kind.
REGISTER 12-1:
DS41291D-page 158
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
Note 1:
R/W-0
CSRC
Clock Accuracy with
Asynchronous Operation
DD
SREN/CREN overrides TXEN in Sync mode.
or temperature changes, and this directly
CSRC: Clock Source Select bit
Asynchronous mode:
Don’t care
Synchronous mode:
1 =
0 =
TX9: 9-bit Transmit Enable bit
1 =
0 =
TXEN: Transmit Enable bit
1 = Transmit enabled
0 = Transmit disabled
SYNC: EUSART Mode Select bit
1 = Synchronous mode
0 = Asynchronous mode
SENDB: Send Break Character bit
Asynchronous mode:
1 = Send Sync Break on next transmission (cleared by hardware upon completion)
0 = Sync Break transmission completed
Synchronous mode:
Don’t care
BRGH: High Baud Rate Select bit
Asynchronous mode:
1 = High speed
0 = Low speed
Synchronous mode:
Unused in this mode
TRMT: Transmit Shift Register Status bit
1 = TSR empty
0 = TSR full
TX9D: Ninth bit of Transmit Data
Can be address/data bit or a parity bit.
R/W-0
TX9
Master mode (clock generated internally from BRG)
Slave mode (clock from external source)
Selects 9-bit transmission
Selects 8-bit transmission
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
W = Writable bit
‘1’ = Bit is set
TXEN
R/W-0
(1)
(1)
R/W-0
SYNC
Preliminary
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
SENDB
R/W-0
The first (preferred) method uses the OSCTUNE
register to adjust the INTOSC output. Adjusting the
value in the OSCTUNE register allows for fine resolution
changes to the system clock source. See 4.5 “Internal
Clock Modes” for more information.
The other method adjusts the value in the Baud Rate
Generator. This can be done automatically with the
Auto-Baud Detect feature (see Section 12.3.1 “Auto-
Baud Detect”). There may not be fine enough
resolution when adjusting the Baud Rate Generator to
compensate for a gradual change in the peripheral
clock frequency.
BRGH
R/W-0
© 2007 Microchip Technology Inc.
x = Bit is unknown
TRMT
R-1
R/W-0
TX9D
bit 0