CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U15195EJ5V0UD
509
(2) Dedicated baud rate generator 3 (BRG3)
BRG3 is configured by an 8-bit timer counter that generates the baud rate signal, prescaler mode register 3
(PRSM3), which controls baud rate signal generation, prescaler compare register 3 (PRSCM3), which sets
the value of the 8-bit timer counter, and a prescaler.
(a) Input clock
The internal system clock (f
XX
) is input to BRG3.
(b) Prescaler mode register 3 (PRSM3)
The PRSM3 register controls generation of the CSI0 and CSI1 baud rate signals.
This register can be read/written in 8-bit or 1-bit units.
Cautions 1. Do not change the value of the BGCS1, BGCS0 bits during a transmission/
reception operation.
2. Set the PRSM3 register prior to setting the CSICAEn bit of the CSIMn register to 1
(n = 0, 1).
7
0
PRSM3
6
0
5
0
4
CE
3
0
2
0
1
BGCS1
0
BGCS0
Address
FFFFF920H
After reset
00H
Bit position
Bit name
Function
4 CE
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 operation.
Selects count clock for baud rate counter.
BGCS1
BGCS0
Count clock selection
0 0
f
XX
/4
0 1
f
XX
/8
1 0
f
XX
/16
1 1
f
XX
/32
1, 0
BGCS1,
BGCS0
Remark
f
XX
: Internal system clock
