Analog Devices ADSP-SC58 Series Hardware Reference Manual page 951

Heightened-Precision Edge Placement
[15:12] of represent the decimal part or heightened-precision value and bits [31:16] represent the coarse
duty cycle.
Sample Waveforms for High- and Low-Side with Precision Placement
When the PWM module uses heightened-precision in the dependent mode of operation, both high and low-side
outputs shift in the same direction. This operation can result in pulse-expansion of the high-side and pulse-contrac-
tion of the low-side or conversely.
The Output Shift in The Same Direction figure shows an example of a case with DT =1, and pulse expansion occurs
on the high-side and pulse-contraction on the low-side. It juxtaposes a case where the PWM module does not use
heightened-precision and a case where PWM does use it.
Figure 19-22: Output Shift in The Same Direction
The following Precision Placement: PULSEMODE figures illustrate the cases for pulse modes 1, 2, and 3 (pulse
mode 00 is a trivial case of pulse mode 01). The pulse modes are configured in the
channel control registers. The figures show what happens to the edges as a decimal part is added to a programmed
positive duty. In each case, assume that the original PWM_AH0.DUTY register value, which is the coarse duty value,
changes to the PWM_AH1.DUTY value after programming the enhanced-resolution (PWM_AH0_HP,
PWM_AH1_HP) registers. For example, changing 14 to 14.25 and 10 to 10.75. The figures are not drawn to these
numbers. For negative duty values, the shifts are in the opposite direction.
19–30 ADSP-SC58x/ADSP-2158x SHARC+ Processor Hardware Reference
and
PWM_ACTL PWM_BCTL