SDHSCTL0.AUTOSSDIS = 0, SDHSCTL2.SMPCTLOFF = 0, SDHSCTL0.INTDLY = 0, SDHSCTL2.SMPSZ = n
SDHS is
Power Off
SDHS Settling Time
Conversion Start
Sample
Conversion
Stop
2nd 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
2nd Sample
> 2/Fs
SDHS Functional Operation
590
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Sigma-Delta High Speed (SDHS)
Table 22-8. Conversion Control Mode
Input Change
SDHSCTL1.OSR
Bit
Fully Settled Output Sample From the
Time a Step Function is Applied
SDHSCTL0.INTDL
Y Value
Synchronous to f
s
10
5th sample
≤
4
20
3th sample
≤
2
40
2th sample
≤
1
80
1st sample
0
160
1st sample
0
Asynchronous to f
s
10
6th sample
≤
5
20
4th sample
≤
3
40
3rd sample
≤
2
80
2nd sample
≤
1
160
2nd sample
≤
1
22.2.10 Total Sample Size
The total number of samples that the SDHS generates can be predefined by SDHSCTL2.SMPSZ when
SDHSCTL2.SMPCTLOFF = 0. The value written to SDHSCTL2.SMPSZ includes the samples skipped by
SDHSCTL0.INTDLY:
•
Total number of samples SDHS generates = SMPSZ + 1 (when SDHSCTL2.SMPCTLOFF = 0)
•
The number of samples that can be read or transferred = SMPSZ – 1 (when
SDHSCTL2.SMPCTLOFF = 0)
When SDHSCTL2.SMPCTLOFF = 0, the SDHS automatically stops data conversion after completing the
number of samples configured in SDHSCTL2.SMPSZ. The SDHSCTL2.SMPSZ bit is ignored when
SDHSCTL2.SMPCTLOFF = 1. In this case, the SDHS continues conversion until it is stopped by the
trigger source. Take care when writing a value to SDHSCTL2.SMPSZ. If SDHSCTL2.SMPSZ –
SDHSCTL0. 1
≤
0, no output data is generated. For example:
If SDHSCTL2.SMPSZ = 10 and SDHSCTL0.INTDLY = 2, then the number of available samples would be
10 – 2 + 1 = 9.
Figure 22-24. SDHSCTL0.AUTOSSDIS = 0, SDHSCTL2.SMPCTLOFF = 0, SDHSCTL0.INTDLY = 0, Total
Sample Size is Controlled by SDHSCTL2.SMPSZ