Epson S1C6S3N2, Technical Manual

Page: 76 / 270

I-64
EPSON
S1C6S3N2 TECHNICAL HARDWARE
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Clock Timer)
The 16 Hz–2 Hz timer data of the clock timer can be read
out with this register. These four bits are read-out only, and
writing operations are invalid.
At initial reset, the timer data is initialized to "0H".
These registers are used to select whether to mask the clock
timer interrupt.
When "1" is written : Enabled
When "0" is written : Masked
Read-out : Valid
The interrupt mask registers (ETI32, ETI8, ETI2) are used to
select whether to mask the interrupt to the separate fre-
quencies (32 Hz, 8 Hz, 2 Hz).
At initial reset, these registers are all set to "0".
These flags indicate the status of the clock timer interrupt.
When "1" is read out : Interrupt has occurred
When "0" is read out : Interrupt has not occurred
Writing : Invalid
The interrupt factor flags (TI32, TI8, TI2) correspond to the
clock timer interrupts of the respective frequencies (32 Hz, 8
Hz, 2 Hz). The software can judge from these flags whether
there is a clock timer interrupt. However, even if the inter-
rupt is masked, the flags are set to "1" at the falling edge of
the signal.
These flags can be reset through being read out by the
software.
Reading of interrupt factor flags is available at EI, but be
careful in the following cases.
If the interrupt mask register value corresponding to the
interrupt factor flags to be read is set to "1", an interrupt
request will be generated by the interrupt factor flags set
timing, or an interrupt request will not be generated.
Be very careful when interrupt factor flags are in the same
address.
At initial reset, these flags are set to "0".
TM0–TM3:
Timer data
(070H)
ETI32, ETI8, ETI2:
Interrupt mask registers
(078H·D0–D2)
TI32, TI8, TI2:
Interrupt factor flags
(079H·D0–D2)