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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
1346 of 1441
NXP Semiconductors
UM10503
Chapter 48: 12-bit ADC (ADCHS)
48.6.14 Descriptor table 0 register
These registers contain the descriptor entries of table 0. Register 0x44n
contains descriptor n (n=0,1...7). The analog to digital conversion time and sequence are
controlled by descriptor table entries and the 14-bit descriptor timer. The descriptor timer
operates at fADC, it wraps around to 0x0000 after reaching its maximum value 0x3FFF.
The timer can be reset by field RESET_TIMER. HALT halts the descriptor processing but
the timer continues running. Processing restarts at a new input trigger.
A sample at input channel CHANNEL_NR is converted when the descriptor timer equals
field MATCH_VALUE.
An input channel can be linked to window comparator A or B by field TRESHOLD_SEL.
When INTERRUPT is set interrupt 0 can be raised when the conversion results is
available in the output FIFO or LAST_SAMPLE register and the mask bit associated with
DSCR_DONE is set by register SET_EN0.
When POWER_DOWN is set the ADC is powered down after the conversion has finished.
The ADC is automatically woken up before the next conversion. Wake up time is set in
RECOVERY_TIME (see
), this is default 144 fADC cycles.
Remark:
If the first descriptor is required earlier than RECOVERY_TIME, then automatic
wake up cannot be used. In that case the previous descriptor should not set
POWER_DOWN.
Table 1136.FIFO output register (FIFO_OUTPUT[0:15], address 0x400F 0200
(FIFO_OUTPUT0) to 0x400F 0203C (FIFO_OUTPUT15)) bit description
Bit
Symbol
Description
Reset
value
11:0
SAMPLE
Value of first converted sample
0x0
14:12
CHAN_ID
Channel number of first converted sample:
000: channel _0 or CHANNEL_ID_EN =0
001: channel _1
010: channel _2
011: channel _3
100: channel _4
101: channel _5
110: reserved
111: recovery_ error
0x0
15
EMPTY
0: FIFO not empty
1: FIFO empty
0x1
27:16
SAMPLE2
Value of second converted sample.
This field is only valid if PACKED_READ is set else it is 0x0
0x0
30:28
CHAN_ID2
Channel number of second converted sample
This field is only valid if CHANNEL_ID_EN and
PACKED_READ are set else it is 0x0
0x0
31
EMPTY2
0: FIFO not empty
1: FIFO empty and PACKED_READ is set
0x0