Precision ADC Operation
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SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Precision ADC
22.2.8.5 Using the Multiple Sample and Convert (ADC14MSC) Bit
To configure the converter to perform successive conversions automatically and as quickly as possible, a
multiple sample and convert function is available. When ADC14MSC = 1, CONSEQx > 0, and the sample
timer is used, the first rising edge of the SHI signal triggers the first conversion. Successive conversions
are triggered automatically as soon as the prior conversion is completed. Additional rising edges on SHI
are ignored until the sequence is completed in the single-sequence mode, or until the ADC14ENC bit is
toggled in repeat-single-channel or repeated-sequence modes. The function of the ADC14ENC bit is
unchanged when using the ADC14MSC bit.
22.2.8.6 Stopping Conversions
Stopping Precision ADC activity depends on the mode of operation. The recommended ways to stop an
active conversion or conversion sequence are:
•
Set ADC14ENC = 0 in single-channel single-conversion mode to stop a conversion immediately. The
results are unreliable. For reliable results, poll the busy bit until it is reset before clearing ADC14ENC.
•
Set ADC14ENC = 0 during repeat-single-channel operation to stop the converter at the end of the
current conversion.
•
Set ADC14ENC = 0 during a sequence or repeat-sequence mode to stop the converter at the end of
the current conversion.
•
To stop conversion immediately in any mode, set CONSEQx = 0 and ADC14ENC = 0. In this case,
conversion data are unreliable.
NOTE:
No ADC14EOS bit set for sequence
If no ADC14EOS bit is set and a sequence mode is selected, resetting the ADC14ENC bit
does not stop the sequence. To stop the sequence, first select a single-channel mode and
then reset ADC14ENC.
22.2.9 Window Comparator
The window comparator allows to monitor analog signals without any CPU interaction. It is enabled for the
desired ADC14MEMx conversion with the ADC14WINC bit in the ADC14MCTLx register. The window
comparator interrupts are:
•
The ADC14LO interrupt flag (ADC14LOIFG) is set if the current result of the Precision ADC conversion
is less than the low threshold defined in register ADC14LO.
•
The ADC14HI interrupt flag (ADC14HIIFG) is set if the current result of the Precision ADC conversion
is greater than the high threshold defined in the register ADC14HI.
•
The ADC14IN interrupt flag (ADC14INIFG) is set if the current result of the Precision ADC conversion
is greater than or equal to the low threshold defined in register ADC14LO and less than or equal to the
high threshold defined in the register ADC14HI.
These interrupts are generated independent of the conversion mode. The update of the window
comparator interrupt flags happens after the ADC14IFGx.
There are two sets of window comparator threshold registers ADC14LO0, ADC14HI0 and ADC14LO1,
ADC14HI1. The ADC14WINCTH bit in the Conversion Memory Control Register (ADC14MCTLx) selects
between the two sets of window comparator threshold registers. When ADC14WINCTH is set to 0,
ADC14LO0 and ADC14HI0 threshold registers are selected and when ADC14WINCTH is set to 1,
ADC14LO1 and ADC14HI1 threshold registers are selected for memory conversion x.
The lower and higher threshold in the ADC14LOx and ADC14HIx registers must be set in the correct data
format. If the binary unsigned data format is selected by ADC14DF = 0, then the thresholds in the
registers ADC14LOx and ADC14HIx must be written as binary unsigned values. If the signed binary (2s
complement) data format is selected by ADC14DF = 1, then the thresholds in the registers ADC14LOx
and ADC14HIx must be written as signed binary (2s complement). Changing the ADC14DF bit or the
ADC14RES bits reset the threshold registers.