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This chapter explains the operation of the PPG timer.
13.1 Overview of PPG Timer
The PPG timer is composed of prescaler, one 16-bit decrement counter, 16-bit data register with cycle
setting buffer, 16-bit compare register with duty setting buffer, and pin controller.
The PPG timer can output pulses synchronized with an external trigger or software trigger. The cycle and
duty of output pulses can be changed arbitrarily by rewriting the value of the two 16-bit registers.
n Overview
• PWM function
A pulse can be output to the programmable by being synchronized with the trigger and by rewriting the
value of the above registers.
The PWM function can also be used as a D/A converter by an external circuit.
• One-shot function
It is possible to detect the edge of the trigger input and output a single pulse.
• Pin control
– When a duty match occurs, the pin is set to 1 (this is preferred).
– When a borrow occurs in the counter, the pin is reset to 0.
– In the fixed output value mode, all L (or all H) can be output easily.
– The polarity can be specified.
• 16-bit decrement counter
– The counter operating clock can be selected from four types of internal clocks: φ, φ/4, φ/16, and φ/64 (φ:
Machine clock).
– The counter value can be initialized to FFFF
• Interrupt request
– The timer is started.
– A borrow occurs in the counter (cycle match).
– A duty match occurs.
– A borrow occurs in the counter (cycle match) or a duty match occurs.
• A concurrent start for plural channels by the external trigger can be set. Also, a restart during operation
can be set.
PPG TIMER
by a reset or a borrow in the counter.
H
13-3
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