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UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
385 of 464
NXP Semiconductors
UM10850
Chapter 25: LPC5410x 12-bit ADC controller (ADC0)
25.7 Functional description
25.7.1 Conversion Sequences
A conversion sequence is a single pass through a series of ADC conversions performed
on a selected set of ADC channels. Software can configure up to two independent
conversion sequences, either of which can be triggered by software or by a transition on
one of the hardware triggers. Each sequence can be triggered by a different hardware
trigger. One of these conversion sequences is referred to as the A sequence and the other
as the B sequence.
An optional single-step mode allows advancing through the channels of a sequence one
at a time on each successive occurrence of a trigger.
The user can select whether a trigger on the B sequence can interrupt an already
in-progress A sequence. The B sequence, however, can never be interrupted by an A
trigger.
25.7.2 Hardware-triggered conversion
Software can select among hardware triggers will launch each conversion sequence and
it can specify the active edge for the selected trigger independently for each conversion
sequence.
For each conversion sequence, if a designated trigger event occurs, one single cycle
through that conversion sequence will be launched unless:
•
The BURST bit in the SEQn_CTRL register for this sequence is set to 1.
•
The requested conversion sequence is already in progress.
•
A set of conversions for the alternate conversion sequence is already in progress
except in the case of a B trigger interrupting an A sequence if the A sequence is set to
LOWPRIO.
If any of these conditions is true, the new trigger event will be ignored and will have no
effect.
In addition, if the single-step bit for a sequence is set, each new trigger will cause a single
conversion to be performed on the next channel in the sequence rather that launching a
pass through the entire sequence.
If the A sequence is enabled to be interrupted (i.e. the LOWPRIO bit in the SEQA_CTRL
register is set) and a B trigger occurs while an A sequence is in progress, then the
following will occur:
•
The ADC conversion which is currently in-progress will be aborted.
•
The A sequence will be paused, and the B sequence will immediately commence.
•
The interrupted A sequence will resume after the B sequence completes, beginning
with the conversion that was aborted when the interruption occurred. The channel for
that conversion will be re-sampled.