Transmission Rate Setting Of Serial Interface - Epson 0C88832 Technical Manual

5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Programmable Timer)
The output control for the TOUT (TOUT) signal is
done by the register PTOUT. When you set "1" for
the PTOUT, the TOUT (TOUT) signal is output
from the R27 (R26) output port terminal. When "0"
is set, the R27 goes HIGH (V
LOW (V ).
SS
To output the TOUT signal, "1" must always be set
for the data register R27D. The data register R26D
does not affect the TOUT output.
Since the TOUT signal is generated asynchronously
from the register PTOUT, when the signal is turned
ON or OFF by the register setting, a hazard of a 1/2
cycle or less is generated.
Figure 5.10.8.3 shows the output waveform of
TOUT signal.
PTOUT 0
TOUT output (R27)
TOUT output (R26) *
∗ when selected by mask option
Fig. 5.10.8.3 TOUT output waveform
82
) and the R26 goes
DD
1
Table 5.10.9.1 Example of transmission rate setting
Transfer rate
(bps)
9,600
4,800
2,400
1,200
600
300
150
EPSON
5.10.9 Transmission rate setting of
serial interface
The underflow signal of the timer 1 can be used to
clock the serial interface.
The transmission rate setting in this case is made in
registers PSC1X and PLD1X, and is used to set the
count mode to the reload count mode (RLMD1 =
"1").
Since the underflow signal of the timer 1 is divided
by 1/32 in the serial interface, the value set in
register RLD1X which corresponds to the transmis-
sion rate is shown in the following expression:
RLD1X = fosc / (32*bps*4
fosc: Oscillation frequency (OSC1/OSC3)
bps: Transmission rate
PSC1X: Setting value to the register PSC1X (0–3)
(00H can be set to RLD1X)
Table 5.10.9.1 shows an example of the transmis-
sion rate setting when the OSC3 oscillation circuit is
used as a clock source.
OSC3 oscillation frequency / Programmable timer settings
f = 3.072 MHz f
OSC3 OSC3
PSC1X RLD1X PSC1X
0 (1/1) 09H 0 (1/1)
0 (1/1) 13H 0 (1/1)
0 (1/1) 27H 0 (1/1)
0 (1/1) 4FH 0 (1/1)
0 (1/1) 9FH 0 (1/1)
1 (1/4) 4FH 1 (1/4)
1 (1/4) 9FH 1 (1/4)
E0C88832/88862 TECHNICAL MANUAL
PSC1X ) - 1
= 4.608 MHz f = 4.9152 MHz
OSC3
RLD1X PSC1X RLD1X
0EH 0 (1/1)
1DH 0 (1/1)
3BH 0 (1/1)
77H 0 (1/1)
EFH 0 (1/1)
77H 1 (1/4)
EFH 1 (1/4)
0FH
1FH
3FH
7FH
FFH
7FH
FFH