CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U15195EJ5V0UD
468
(2) Dedicated baud rate generator 1 (BRG1)
BRG1 is configured of an 8-bit timer counter for baud rate signal generation, a prescaler mode register that
controls the generation of the baud rate signal (PRSM1), a prescaler compare register that sets the value of
the 8-bit timer counter (PRSCM1), and a prescaler.
(a) Input clock
The internal system clock (f
XX
) is input to BRG1.
(b) Prescaler mode register 1 (PRSM1)
The PRSM1 register controls generation of the UART1 baud rate signal.
These registers can be read/written in 8-bit or 1-bit units.
Cautions 1. Do not change the values of the BGCS1 and BGCS0 bits during transmission/
reception operations.
2. Set PRSM1 bits other than the UARTCE1 bit prior to setting the UARTCE1 bit to 1.
<7>
UARTCE1
PRSM1
6
0
5
0
4
0
3
0
2
0
1
BGCS1
0
BGCS0
Address
FFFFFA2EH
After reset
00H
Bit position
Bit name
Function
7 UARTCE1
Enables baud rate counter operation.
0: Stops baud rate counter operation and fixes baud rate output signal to 0.
1: Enables baud rate counter operation and starts baud rate output.
Selects count clock to baud rate counter.
BGCS1
BGCS0
Count clock selection
0 0
f
XX
/2
0 1
f
XX
/4
1 0
f
XX
/8
1 1
f
XX
/16
1, 0
BGCS1,
BGCS0
Remark
f
XX
: Internal system clock
