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PCM-3780 User Manual 56
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
VALUE
TC OUTPUT
TC TOGGLED
OUTPUT
Mode J
Waveforms
H H-1 H-2 2 1 L L-2 2 1 0 H H-12 1 0 0 L-1 H-2