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

EM78P312N

8-Bit Microcontroller

				TC4M (1,1)	TC4FF
					TC4 Interrupt
					F/F	/PWM, /PDO Pin
11			Clear		Clear
						Q
fc/2				TC4M(1,*)	Set
fc/2 7	MUX		8-bit Up-counter		Toggle
fc/2 3				Overflow
TC4 pin				Match
				Comparator
	TC4CK	3
		TC4S
		TC4CR	TCR4
			Fig. 5-24	Timer/Counter 4 Configuration

5.11.1 Timer Mode

In Timer mode, counting up is performed using the internal clock. When the contents of the up-counter matched with the TCR4, then interrupt is generated and the counter is cleared. Counting up resumes after the counter is cleared.

5.11.2 Counter Mode

In Counter mode, counting up is performed on the rising edge of the external clock input pin (TC4 pin). When the contents of the up-counter matched with the TCR4, then interrupt is generated and the counter is cleared. Counting up resumes after the counter is cleared.

5.11.3 PDO Mode

In Programmable Divider Output (PDO) mode, counting up is performed using the internal clock. The contents of TCR4 are compared with the contents of the up-counter. The F/F output is toggled and the counter is cleared each time a match is found. The F/F output is inverted and output to /PDO pin. This mode can generate 50% duty pulse output. The F/F can be initialized by the program and it is initialized to “0” during a reset. A TC4 interrupt is generated each time the /PDO output is toggled.

Source Clock
Up-counter	0	1	2	3	n-1	n	0	1	n-1	n	0	1	n-1	n	0	1	2
TCR4		n
F/F
/PDO Pin
TC4 Interrupt

Fig. 5-25 Timing Chart for PDO Mode

40 • Product Specification (V1.0) 10.03.2006

(This specification is subject to change without further notice)