Intel 8XC196MD manual Frequency Generator Signal, Frequency Generator Control and Status Registers

8XC196MC, MD, MH USER’S MANUAL

The frequency register (FREQ_GEN) controls the output frequency. The frequency generator loads the FREQ_GEN value into the counter. The counter counts down until it reaches zero, at which time the value is reloaded from the FREQ_GEN register. Each load toggles the D flip-flop, producing the 50% duty cycle output. The count register (FREQ_CNT) reflects the current value of the down-counter. Table 8-1 describes the frequency generator’s output signal and Table 8-2 describes the control and status registers.

Table 8-1. Frequency Generator Signal

Port		Frequency			Frequency
		Generator			Generator		Description
Pin
		Signal		Signal Type
P7.7	FREQOUT					O	Frequency Generator Output
							This signal carries the output of the frequency generator.
.
		Table 8-2. Frequency Generator Control and Status Registers
Mnemonic			Address				Description
FREQ_GEN			1FB8H			Frequency
						The frequency register holds a programmed value that determines the
						output frequency. This value is reloaded into the down-counter each time the
						counter reaches 0.
FREQ_CNT			1FBAH			Count
						The read-only counter register reflects the current counter value.
P7_DIR			1FD3H			Port 7 Direction
						Bit 7 controls the direction of P7.7/FREQOUT. Clear this bit to configure
						FREQOUT as a complementary output.
P7_MODE			1FD1H			Port 7 Mode
						Bit 7 controls the mode (general-purpose I/O or special-function signal) of
						P7.7/FREQOUT. Set this bit to configure the pin for its FREQOUT function.
P7_PIN			1FD7H			Port 7 Input
						Bit 7 reflects the current state of P7.7/FREQOUT, regardless of its configu-
						ration.
P7_REG			1FD5H			Port 7 Data Output
						Bit 7 contains data to be driven out by P7.7/FREQOUT in general-purpose
						I/O mode. In special-function mode, the frequency generator controls the
						pin.

8-2