DocID025202 Rev 7
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RM0365
Analog-to-digital converters (ADC)
392
JADSTART is cleared by hardware:
•
in single mode with software injected trigger (JEXTSEL=0x0)
–
at any end of injected conversion sequence (JEOS assertion) or at any end of
sub-group processing if JDISCEN = 1
•
in all cases (JEXTSEL=x)
–
after execution of the JADSTP procedure asserted by the software.
15.3.16 Timing
The elapsed time between the start of a conversion and the end of conversion is the sum of
the configured sampling time plus the successive approximation time depending on data
resolution:
Figure 58. Analog to digital conversion time
1. T
SMPL
depends on SMP[2:0]
2. T
SAR
depends on RES[2:0]
15.3.17 Stopping
an
ongoing
conversion (ADSTP, JADSTP)
The software can decide to stop regular conversions ongoing by setting ADSTP=1 and
injected conversions ongoing by setting JADSTP=1.
Stopping conversions will reset the ongoing ADC operation. Then the ADC can be
reconfigured (ex: changing the channel selection or the trigger) ready for a new operation.
Note that it is possible to stop injected conversions while regular conversions are still
operating and vice-versa. This allows, for instance, re-configuration of the injected
conversion sequence and triggers while regular conversions are still operating (and vice-
versa).
When the ADSTP bit is set by software, any ongoing regular conversion is aborted with
partial result discarded (ADCx_DR register is not updated with the current conversion).
T
ADC
= T
SMPL
+ T
SAR
= [ 1.5
|min
+ 12.5
|12bit
] x T
ADC_CLK
T
ADC
= T
SMPL
+ T
SAR
= 20.83 ns
|min
+ 173.6 ns
|12bit
= 194.4 ns (for F
ADC_CLK
= 72 MHz)
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