NEC mPD789026 Subseries, Руководство пользователя

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CHAPTER 9 SERIAL INTERFACE 00
User's Manual U11919EJ3V0UM00
147
(c) Baud rate generator control register 00 (BRGC00)
BRGC00 is set with an 8-bit memory manipulation instruction.
RESET input clears BRGC00 to 00H.
TPS003
0
0
0
0
0
0
0
0
TPS003 TPS002 TPS001 TPS000 0 0 0 0 BRGC00
R/W
FF73H 00H R/W
7 6 5 4 3 2 1 0
TPS002
0
0
0
0
1
1
1
1
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)
TPS001
0
0
1
1
0
0
1
1
TPS000
0
1
0
1
0
1
0
1
n
1
2
3
4
5
6
7
8
Setting prohibited
Symbol Address After Reset
3-Bit Counter Source Clock Selection
Other than above
Cautions 1. When writing to BRGC00 is performed during a communication operation, the
baud rate generator output is disrupted and communications cannot be performed
normally. Be sure not to write to BRGC00 during communication operation.
2. Be sure not to select n = 1 during an operation at f
X
= 5.0 MHz because n = 1
exceeds the baud rate limit.
3. When selecting an input clock from an external source, set port mode register 2
(PM2) to the input mode.
Remarks 1. f
X
: System clock oscillation frequency
2. n : Value determined by setting TPS000 through TPS003 (1
≤
n
≤
8)
3. The parenthesized values apply to operation at f
X
= 5.0 MHz.
If the internal clock is used as the serial clock for 3-wire serial I/O mode, set the TPS000 to TPS003 bits
to set the frequency of the serial clock. To obtain the frequency to be set, use the following formula.
When the serial clock is input from external, setting BRGC00 is not necessary.
Serial clock frequency = [Hz]
f
X
: System clock oscillation frequency
n : Value determined by setting TPS000 through TPS003 as shown in the above table (1
≤
n
≤
8)
f
X
2
n + 1