NEC mPD789425, User Manual

Page: 228 / 321

CHAPTER 12 SERIAL INTERFACE 20
User’s Manual U15075EJ1V0UM00
228
(d) Baud rate generator control register 20 (BRGC20)
BRGC20 is set with an 8-bit memory manipulation instruction.
RESET input sets BRGC20 to 00H.
TPS203
0
0
0
0
0
0
0
0
1
TPS202
0
0
0
0
1
1
1
1
0
f
X
/2
f
X
/2
2
f
X
/2
3
f
X
/2
4
f
X
/2
5
f
X
/2
6
f
X
/2
7
f
X
/2
8
(2.5 MHz)
(1.25 MHz)
(625 kHz)
(313 kHz)
(156 kHz)
(78.1 kHz)
(39.1 kHz)
(19.5 kHz)
TPS201
0
0
1
1
0
0
1
1
0
TPS200
0
1
0
1
0
1
0
1
0
n
1
2
3
4
5
6
7
8
−
Setting prohibited
3-bit counter source clock selection
External clock input to ASCK20 pin
Note
Other than above
TPS203 TPS202 TPS201 TPS200 0 0 0 0 BRGC20
7 6 5 4 Symbol Address After reset R/W
FF73H 00H R/W
3 2 1 0
Note Can only be used in the UART mode.
Cautions 1. When writing to BRGC20 during a communication operation, the output of the
baud rate generator is disrupted and communications cannot be performed
normally. Be sure not to write to BRGC20 during a communication operation.
2. Be sure not to select n = 1 during operation at f
X
= 5.0 MHz because the resulting
baud rate exceeds the rated range.
3. When the external input clock is selected, set port mode register 2 (PM2) to input
mode.
Remarks 1. f
X
: Main system clock oscillation frequency
2. n: Values determined by the settings of TPS200 to TPS203 (1
≤
n
≤
8)
3. The parenthesized values apply to operation at f
X
= 5.0 MHz.