335
XMEGA B [DATASHEET]
8291B–AVR–01/2013
26.11 DMA Transfer
The DMA controller can be used to transfer ADC conversion results to memory or other peripherals. A new conversion
result can trigger a DMA transaction. Refer to
“DMAC - Direct Memory Access Controller” on page 49
DMA transfers.
26.12 Interrupts and Events
The ADC can generate interrupt requests and events. The ADC channel has individual interrupt settings and interrupt
vectors. Interrupt requests and events can be generated when an ADC conversion is complete or when an ADC
measurement is above or below the ADC compare register value.
26.13 Calibration
The ADC has built-in linearity calibration. The value from the production test calibration must be loaded from the
signature row and into the ADC calibration register from software to achieve specified accuracy. User calibration of the
linearity is not needed, hence not possible. Offset and gain calibration must be done in software.
26.14 Synchronous Sampling
Starting an ADC conversion can cause an unknown delay between the start trigger or event and the actual conversion
since the peripheral clock is faster than the ADC clock. To start an ADC conversion immediately on an incoming event, it
is possible to flush the ADC of all measurements, reset the ADC clock, and start the conversion at the next peripheral
clock cycle (which then will also be the next ADC clock cycle). If this is done, the ongoing conversions in the ADC will be
lost.
The ADC can be flushed from software, or an incoming event can do this automatically. When this function is used, the
time between each conversion start trigger must be longer than the ADC propagation delay to ensure that one
conversion is finished before the ADC is flushed and the next conversion is started.
It is also important to clear pending events or start ADC conversion commands before doing a flush. If not, pending
conversions will start immediately after the flush.
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