Texas Instruments MSP430x1xx - Manual (Page 303)

Conversion Modes
15-13
ADC12
no sample-and-conversion is active, or after an active sample-and-conversion
is completed. The original sequence may not be completed, but all completed
conversion results are valid. See also the
Switching Between Conversion
Modes section.
If the conversion mode is changed after the sequence begins, but before it has
completed, and the ENC bit is toggled, then the original sequence completes
normally and the new mode takes effect and is started after the original se-
quence completes – unless the new mode is
single-channel single-conver-
sion. If the new mode is single-channel single-conversion, then the original se-
quence stops when no sample-and-conversion is active, or after an active
sample-and-conversion is completed, or when the ENC bit is reset, whichever
comes first. Then, the single conversion begins when the ENC bit is set again.
See also the
Switching Between Conversion Modes section.
Figure 15–7. ENC Does Not Effect Active Sequence
ENC
SAMPCON
ENC and ADC12SC
may be set together
ADC12SC reset
starts conversion
ADC12SC set
starts sampling
ADC12SC reset
starts conversion
Period of Sequences
ADC12SC set
starts sampling
ADC12SC reset
starts conversion
Next Period of Sequences
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Sample Conversion Sample Conversion Sample Conversion Sample Conversion Sample Conversion
Single Period
of Sequence
Single Period
of Sequence
Single Period
of Sequence
Single Period
of Sequence
ENC
First +SAMPCON with
ENC set start S&C
ADC12SC reset
starts conversion
ADC12SC set
starts sampling
ADC12SC reset
starts conversion
ADC12SC set
starts sampling
ADC12SC reset
starts conversion
SAMPCON
Period of Sequences Next Period of Sequences
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Single Conversion
Time
Sample Conversion Sample Conversion Sample Conversion Sample Conversion Sample Conversion
Single Period
of Sequence
Single Period
of Sequence
Single Period
of Sequence
Single Period
of Sequence
An active sequence may be stopped immediately by selecting single-channel
single-conversion mode (reset CONSEQ.1 bit) and then resetting the
enable-conversion bit ENC. The data in memory register ADC12MEMx is
unpredictable and the interrupt flag ADC12IFG.x may or may not be set. This
is generally not recommended but may be used as an emergency exit.
Each time a conversion is completed, the results are loaded into the appropri-
ate ADC12MEMx register and the corresponding interrupt flag ADC12IFG.x
is set to indicate completion of the conversion. Additionally, If the appropriate
interrupt-enable flags are set, an interrupt request is generated (see the
ADC12 Interrupt Vector Register ADC12IV section).