I-108
EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Programmable Timer)
PTOUT
TOUT output (R27)
01
Fig. 5.11.8.3 Output waveform of the TOUT signal
5.11.9 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*4PSC1X) - 1
fosc:
Oscillation frequency (OSC1/OSC3)
bps:
Transmission rate
PSC1X:
Setting value to the register PSC1X (0–3)
(00H can be set to RLD1X)
Table 5.11.9.1 shows an example of the transmis-
sion rate setting when the OSC3 oscillation circuit is
used as a clock source.
Table 5.11.9.1 Example of transmission rate setting
The output control of the TOUT signal is done by
register PTOUT. When "1" is set to the PTOUT, the
TOUT signal is output from the R27 output port
and when "0" is set, HIGH (VDD) level is output. At
this time, "1" must always be set in the data register
R27D.
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 5.11.8.3 shows the output waveform of
TOUT signal.
Transfer rate
(bps)
9,600
4,800
2,400
1,200
600
300
150
OSC3 oscillation frequency / Programmable timer settings
fOSC3 = 3.072 MHz
PSC1X
0 (1/1)
1 (1/4)
RLD1X
09H
13H
27H
4FH
9FH
4FH
9FH
fOSC3 = 4.608 MHz
PSC1X
0 (1/1)
1 (1/4)
RLD1X
0EH
1DH
3BH
77H
EFH
77H
EFH
fOSC3 = 4.9152 MHz
PSC1X
0 (1/1)
1 (1/4)
RLD1X
0FH
1FH
3FH
7FH
FFH
7FH
FFH