IBM EM78P312N manual Timer Mode, Counter Mode, Capture Mode, Bit Microcontroller

EM78P312N

8-Bit Microcontroller

				Rising	Inhibit
			Edge	Falling	Capture	TC3
			Detector		Control
			INT3ES			Interrupt
			TC3M
TC3 pin			M
fc/2 12 , fs/2 4			MUX			Overflow
10	,	2				8-bit Up-counter
fc/2		fs/2
fc/27
				TC3S
			TC2CK			Comparator
				CAP
			2
				Capture		Capture
			TC3CR		TCR3B	TCR3A
				Fig. 5-22 Configuration of Timer/Counter3

5.10.1 Timer Mode

In Timer mode, counting up is performed using the internal clock. When the contents of the up-counter matched with the TCR3DA, then interrupt is generated and the counter is cleared. Counting up resumes after the counter is cleared. The current contents of the up-counter are loaded into the TCR3DB by setting TC3CAP to “1” and the TC3CAP is cleared to “0” after capture automatically.

5.10.2 Counter Mode

In Counter mode, counting up is performed using the external clock input pin (TC3 pin) and either rising or falling edge can be selected by INT3ES0 but both edge cannot be used. When the contents of the up-counter matched with the TCR3DA, then interrupt is generated and the counter is cleared. Counting up resumes after the counter is cleared. The current contents of the up-counter are loaded into the TCR3DB by setting TC3CAP to “1” and the TC3CAP is cleared to “0” after capture automatically.

5.10.3 Capture Mode

In Capture mode, the pulse width, period and duty of the TC3 input pin are measured in this mode, which can be used in decoding the remote control signal. The counter is free running by the internal clock. On the rising (falling) edge of TC3 pin input, the contents of the counter is loaded into TCR3DA, then the counter is cleared and interrupt is generated. On the falling (rising) edge of TC3 pin input, the contents of the counter are loaded into TCR3DB. The counter is still counting, on the next rising edge

38 • Product Specification (V1.0) 10.03.2006

(This specification is subject to change without further notice)