Intel 8XC196MC manual Determining the Waveform GENERATOR’S Status, Wgcounter, Xxxxh, Counter Value

WAVEFORM GENERATOR

9.5DETERMINING THE WAVEFORM GENERATOR’S STATUS

Read WG_CONTROL (Figure 9-12 on page 9-18) to determine the current dead-time value, counter status, count direction, and operating mode. Read WG_COUNTER (Figure 9-13) to de- termine the current counter value.

WG_COUNTER	Address:	1FCAH
	Reset State (MC, MD):	XXXXH
	Reset State (MH):	0000H

You can read the waveform generator counter (WG_COUNTER) register to determine the current counter value.

15	0
	Counter Value
Bit	Function
Number
15:0	Counter Value
	This register reflects the current counter value.

Figure 9-13. Waveform Generator Counter (WG_COUNTER) Register

9.6ENABLING THE WAVEFORM GENERATOR INTERRUPTS

The waveform generator can generate two types of interrupt requests. The WG interrupt request is triggered by the counter, while the EXTINT interrupt is triggered by an external event.

Mode 0 generates a WG interrupt request once per period, when the counter reaches the WG_RELOAD value. Mode 1 generates a WG interrupt request twice per period, first when the counter reaches 1 and again when it reaches the WG_RELOAD value. The edge-aligned modes generate a WG interrupt request once at the end of each period, when the counter is reloaded with 1.

The protection circuitry controls the EXTINT interrupt. Two bits in the protection register control the type of external event that will generate an interrupt request: a falling or rising edge or a low or high level. (See “Controlling the Protection Circuitry and EXTINT Int errupt Generation” on page 9-15.)

The edge detection circuitry requires a signal to remain asserted for at least 2 state times to be considered a valid edge. The sample circuitry requires a signal to remain asserted for at least 24 state times to be considered a valid level. It samples the input level 3 times during this 24-state period and recognizes the signal as valid only if it is asserted for each sample. Level sampling is useful for environments in which noise spikes might cause unintended interrupts if edge detection were used.

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