SDHSCTL0.AUTOSSDIS = 0, SDHSCTL2.SMPCTLOFF =0, SDHSCTL0.INTDLY = m, SDHSCTL2.SMPSZ = n, where n >> m
SDHS is
Power Off
SDHS Settling Time
Conversion Start
Sample
Conversion
Stop
(m+1)th Sample
(n + 1) th
Sample
SDHSCTL4.SDHSON or
ASQ_ACQARM
ACQDONE Interrupt
SDHSCTL5.SDHS_LOCK bit
(Read Only)
SDHS is Off
SDHS remains on
SDHS Settling Time
Conversion Start
Sample
> 2/Fs
First Output
Sample
SDHSCTL0.AUTOSSDIS = 1, SDHSCTL2.SMPCTLOFF = 0, SDHSCTL0.
SDHSCTL2.SMPSZ = n:
INTDLY = 0,
SDHS is Power Off
SDHS Settling Time
Conversion Start
First Sample
Conversion
Stop
Second Sample (n + 1) th
Sample
SDHS remains on
SDHSCTL4.SDHSON or
ASQ_ACQARM
SDHSCTL5.SSTART or
ASQ_ACQTRIG
Conversion
Start
First Sample
Second Sample
> 2/Fs
ACQDONE Interrupt
SDHSCTL5.SDHS_LOCK bit
(Read Only)
Conversion
Conversion
Conversion
Conversion
SDHS Functional Operation
591
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Sigma-Delta High Speed (SDHS)
Figure 22-25. SDHSCTL0.AUTOSSDIS = 1, SDHSCTL2.SMPCTLOFF = 0, SDHSCTL0.INTDLY = 0, Total
Sample Size is Controlled by SDHSCTL2.SMPSZ
Figure 22-26. SDHSCTL0.AUTOSSDIS = 1, SDHSCTL2.SMPCTLOFF = 0, SDHSCTL0.INTDLY = m, Total
Sample Size is Controlled by SDHSCTL2.SMPSZ
When data conversion has stopped or SDHS has been powered down, 2 sample periods must pass
before starting a new data conversion or turning SDHS on (see
and
•
SDHS output sampling period = SDHSCTL1.OSR / PLL output clock frequency (= SDHS modulator
sampling frequency).
•
SDHS output sampling frequency = PLL output clock frequency (= SDHS modulator sampling
frequency) / SDHSCTL1.OSR.
22.2.11 Window Comparator
The window comparator can monitor data range without CPU interventions. The window comparator is
enabled by the SDHSCTL2.WINDMPEN bit. The comparator compares the latest conversion result
against the value in the SDHSWINHITH register and the SDHSWINLOTH register, then asserts
SDHSRIS.WINHI (window high interrupt flag) if the conversion result is higher than the value in
SDHSWINHITH register, or asserts SDHSRIS.WINLO (window low interrupt flag) if the conversion result is
lower than the value in SDHSWINLOTH register. The window comparison is always performed with the
latest output data before it goes to the internal buffer (see
for details about the internal
buffer). The window comparison is functional even when the internal buffer is full; however, the internal
buffer stops taking new data, so the sample that caused either the SDHSRIS.WINHI or SDHSRIS.WINLO
interrupt cannot be read by the SDHSDT register. The application must ensure that the values in the
SDHSWINHITH and SDHSWINLOTH registers are in the correct data format. The interrupt flags (WINHI
and WINLO) must be reset by user software.