CHAPTER 12 SERIAL INTERFACE 20
User’s Manual U15075EJ2V1UD
222
(4) Baud rate generator control register 20 (BRGC20)
BRGC20 is used to specify the serial clock for serial interface 20.
BRGC20 is set with an 8-bit memory manipulation instruction.
RESET input sets BRGC20 to 00H.
Figure 12-6. Format of Baud Rate Generator Control Register 20
TPS203
0
0
0
0
0
0
0
0
1
Selection of source clock for baud rate generator
TPS203 TPS202 TPS201 TPS200
0
0
0
0
BRGC20
Symbol
Address
After reset
R/W
FF73H
00H
R/W
7
6
5
4
3
2
1
0
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
External clock input to the ASCK20 pin
Note
Setting prohibited
(2.5 MHz)
(1.25 MHz)
(625 kHz)
(313 kHz)
(156 kHz)
(78.1 kHz)
(39.1 kHz)
(19.5 kHz)
Other than above
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
−
Note
An external clock can be used only in UART mode.
Cautions 1. When writing to BRGC00 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 BRGC00 during a communication operation.
2. Be sure not to select n = 1 during operation at f
X
> 2.5 MHz in UART mode 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.
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