Advantech PCM-3780 Mode J Waveforms, Variable Duty Cycle Rate Generator with No Hardware Gating

D.11 Mode J Waveforms

Variable Duty Cycle Rate Generator with No Hardware Gating

Mode J will find the greatest usage in frequency generation applications with variable duty cycle requirements. Once armed, the counter will count continuously until it is issued a DISARM command.

On the first TC, the counter will be reloaded from the Hold register. Counting will then proceed until the second TC at which time the counter will be reloaded from the Load register. Counting will continue, with the reload source alternating on each TC, until a DISARM command is issued to the counter. (The third TC reloads form the Hold register, the fourth TC reloads form the Load register, etc.)

Specifying the TC Toggled output in the Counter Mode register can gen- erate a variable duty cycle output. The Load and Hold values then directly control the output duty cycle, with high resolution available when rela- tively high count values are used.

SOURCE
COUNT	2	1	0	H	H-1 H-2	2	1	0	L	L-1 L-2	2	1	0	H	H-1 H-2
VALUE

TC OUTPUT

TC TOGGLED

OUTPUT

Mode J

Waveforms

PCM-3780 User Manual 56