
S1C88409 TECHNICAL MANUAL
EPSON
109
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (16-bit Programmable Timer)
5.12 16-bit Programmable Timer
5.12.1 Configuration of 16-bit
programmable timer
The S1C88409 has a 16-bit programmable timer
built-in. The timer consists of a 16-bit presettable
down counter, and can be used as 16-bit
× 1
channel or 8-bit
× 2 channels of programmable
timer. Furthermore, they function as event
counters using the input port terminal.
Figure 5.12.1.1 shows the configuration of the 16-
bit programmable timer.
Two 8-bit down counters, two reload data registers
(RDR0, RDR1) and the compare data registers
(CDR0, CDR1) corresponding to each down
counter are arranged in the 16-bit programmable
timer.
The reload data register is used to set an initial
value to the down counter.
The compare data register stores data for compari-
son with the content of the down counter.
By setting these registers, a TOUT signal is gener-
ated, and it can be output to external devices.
Data
bus
8-bit reload data register (RDR0)
8-bit down counter (PTM0)
8-bit compare data register (CDR0)
Timer 0 control registers
Control circuit
Clock selection
circuit
Prescaler/clock
control circuit
Clock output circuit
Comparator
Underflow
Underflow signal
INCL00
fOSC3/fOSC1
Input port
Clock output
EXCL00
TOUT0
Underflow
interrupt
Compare match
interrupt
Compare match
Timer 0
Interrupt circuit
8-bit reload data register (RDR1)
8-bit down counter (PTM1)
8-bit compare data register (CDR1)
Timer 1 control registers
Control circuit
Clock selection
circuit
Prescaler/clock
control circuit
Clock output circuit
Comparator
Underflow
INCL01
fOSC3/fOSC1
Input port
Clock output
EXCL01
TOUT1
Underflow
interrupt
Compare match
interrupt
Compare match
Timer 1
Interrupt circuit
Fig. 5.12.1.1 Configuration of 16-bit programmable timer