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EPSON
S1C63666 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Programmable Timer)
4.11.6 Interrupt function
The programmable timer can generate an interrupt due to an underflow of each timer. See Figure 4.11.2.1
for the interrupt timing.
An underflow of timer x sets the corresponding interrupt factor flag IPTx to "1", and generates an inter-
rupt. The interrupt can also be masked by setting the corresponding interrupt mask register EIPTx.
However, the interrupt factor flag is set to "1" by an underflow of the corresponding timer regardless of
the interrupt mask register setting.
When timers 0 and 1 are used as a 16-bit timer, an interrupt is generated by an underflow of timer 1. In
this case, IPT0 is not set to "1" by a timer 0 underflow.
4.11.7 Control of TOUT output
The programmable timer can generate a TOUT signal due to an underflow of a timer. The TOUT signal is
generated by dividing the underflows in 1/2. It is possible to select which timer's underflow is to be used
by the TOUT output channel selection register CHSEL0–CHSEL1.
Table 4.11.7.1 Selecting a timer for TOUT output
CHSEL1
1
0
0
CHSEL0
∗
1
0
TOUT output timer
Timer 2
Timer 1
Timer 0
Select timer 1 when generating the TOUT signal from the 16-bit timer output.
The TOUT signal can be output from the R02 output port terminal. Programmable clocks can be supplied
to external devices.
Figure 4.11.7.1 shows the configuration of the output port R02.
Data bus
Register
PTOUT
Register
R02
TOUT
R02
(TOUT)
Register
R02HIZ
Fig. 4.11.7.1 Configuration of R02
The output of a TOUT signal is controlled by the PTOUT register. When "1" is written to the PTOUT
register, the TOUT signal is output from the R02 output port terminal and when "0" is written, the
terminal goes to a high (V
DD
) level. However, the data register R02 must always be "1" and the high
impedance control register R02HIZ must always be "0" (data output state).
Since the TOUT signal is generated asynchronously from the PTOUT register, a hazard within 1/2 cycle is
generated when the signal is turned on and off by setting the register.
Figure 4.11.7.2 shows the output waveform of the TOUT signal.
R02HIZ register
R02 register
PTOUT register
TOUT output
Fix at "0"
Fix at "1"
"1"
"0"
"0"
Fig. 4.11.7.2 Output waveform of the TOUT signal
