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UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
387 of 464
NXP Semiconductors
UM10850
Chapter 25: LPC5410x 12-bit ADC controller (ADC0)
If the MODE bit for the sequence is 1 (sequence-complete mode) then the interrupt
flag/DMA request must be written-to by software to clear it (except when used as a DMA
trigger, in which case it will be cleared in hardware by the DMA engine).
25.7.4.2 Threshold-Compare Out-of-Range Interrupt
Every conversion performed on any channel is automatically compared against a
designated set of low and high threshold levels specified in the THRn_HIGH and
THRn_LOW registers. The results of this comparison on any individual channel(s) can be
enabled to cause a threshold-compare interrupt if that result was above or below the
range specified by the two thresholds or, alternatively, if the result represented a crossing
of the low threshold in either direction.
This flag must be cleared by a software write to clear the individual THCMP flags in the
FLAGS register.
25.7.4.3 Data Overrun Interrupt
This interrupt/DMA trigger will be asserted if any of the OVERRUN bits in the individual
channel data registers are set. In addition, the OVERRUN bits in the two sequence global
data (SEQn_GDAT) registers will cause this interrupt/DMA trigger IF the MODE bit for that
sequence is set to 0 (conversion-complete mode).
This flag will be cleared when the OVERRUN bit that caused it is cleared via reading the
register containing it.
Note that the OVERRUN bits in the individual data registers are cleared when data related
to that channel is read from either of the global data registers as well as when the
individual data registers themselves are read.
25.7.5 Optional Operating Modes
There are three optional modes of ADC operation which may be selected in the CTRL
register.
Four alternative ADC accuracy settings are available ranging from 12 bits down to 6 bits of
resolution. Lowering the ADC resolution results in faster conversion times. A single ADC
conversion (including one conversion in a burst or sequence) requires (res3) ADC
clocks when the minimum sampling period is selected. When reduced accuracy is
selected, the unused LSBs of result data will automatically be forced to zero.
Two clocking modes are available, synchronous mode and asynchronous mode. The
synchronous clocking mode uses the system clock in conjunction with an internal.
programmable divider. The main advantage of this mode is determinism. The start of ADC
sampling is always a fixed number of system clocks following any ADC trigger. The
alternative asynchronous mode (on chips where this mode is supported) uses an
independent clock source. In this mode the user has greater flexibility in selecting the
ADC clock frequency to better achieve the maximum ADC conversion rate without
restricting the clock rate for other peripherals. The penalty for using this mode may be
longer latency and greater uncertainty in response to a hardware trigger.