IBM EM78P809N manual PDO Mode, TCR4

EM78P809N

8-Bit Microcontroller

fc/211

fc/2 7

fc/2 3 MUX TC4 pin

TC4CK 3

TC4S

TC4CR

Clear

8-bit Up-counter

TCR4

TC4M (1,1)		TC4FF
		TC4 Interrupt
		F/F	/PWM, /PDO Pin
		Clear
	TC4M(1,*)	Set	Q
		Toggle

Overflow

Match

Comparator

Fig. 25. Timer/Counter 4 Configuration

4.11.1 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.

4.11.2 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.

4.11.3 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

TCR4

F/F /PDO Pin

TC4 Interrupt

0 1 2 3 n-1 n 0 1 n-1 n 0 1 n-1 n 0 1 2

n

	Fig. 26.Timing Chart for PDO Mode
Product Specification (V1.0) 07.26.2005	• 45

(This specification is subject to change without further notice)