UM11029
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User manual
Rev. 1.0 — 16 June 2017
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NXP Semiconductors
UM11029
Chapter 26: LPC84x 12-bit Analog-to-Digital Converter (ADC)
26.6.6 A/D Compare Low Threshold Registers 0 and 1
These registers set the LOW threshold levels against which A/D conversions on all
channels will be compared.
Each channel will either be compared to the THR0_LOW/HIGH registers or to the
THR1_LOW/HIGH registers depending on what is specified for that channel in the
CHAN_THRSEL register.
A conversion result LESS THAN this value on any channel will cause the
THCMP_RANGE status bits for that channel to be set to 0b01. This result will also
generate an interrupt request if enabled to do so via the ADCMPINTEN bits associated
with each channel in the INTEN register.
If, for two successive conversions on a given channel, one result is below this threshold
and the other is equal-to or above this threshold, than a threshold crossing has occurred.
In this case the MSB of the THCMP_CROSS status bits will indicate that a threshold
crossing has occurred and the LSB will indicate the direction of the crossing. A threshold
crossing event will also generate an interrupt request if enabled to do so via the
ADCMPINTEN bits associated with each channel in the INTEN register.
29:26 CHANNEL
This field is hard-coded to contain the channel number that this particular register
relates to (i.e. this field will contain 0b0000 for the DAT0 register, 0b0001 for the DAT1
register, etc)
NA
30
OVERRUN
This bit will be set to a 1 if a new conversion on this channel completes and overwrites
the previous contents of the RESULT field before it has been read - i.e. while the DONE
bit is set.
This bit is cleared, along with the DONE bit, whenever this register is read or when the
data related to this channel is read from either of the global SEQn_GDAT registers.
This bit (in any of the 12 registers) will cause an overrun interrupt request to be
asserted if the overrun interrupt is enabled.
Remark:
While it is allowed to include the same channels in both conversion
sequences, doing so may cause erratic behavior of the DONE and OVERRUN bits in
the data registers associated with any of the channels that are shared between the two
sequences. Any erratic OVERRUN behavior will also affect overrun interrupt
generation, if enabled.
NA
31
DATAVALID
This bit is set to 1 when an A/D conversion on this channel completes.
This bit is cleared whenever this register is read or when the data related to this
channel is read from either of the global SEQn_GDAT registers.
Remark:
While it is allowed to include the same channels in both conversion
sequences, doing so may cause erratic behavior of the DONE and OVERRUN bits in
the data registers associated with any of the channels that are shared between the two
sequences. Any erratic OVERRUN behavior will also affect overrun interrupt
generation, if enabled.
NA
Table 448. A/D Data Registers (DAT[0:11], address 0x4001 C020 (DAT0) to 0x4001 C04C (DAT11)) bit description
Bit
Symbol
Description
Reset
value