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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
1347 of 1441
NXP Semiconductors
UM10503
Chapter 48: 12-bit ADC (ADCHS)
Remark:
When the ADC is switched off (POWER_SWITCH and BGAP_SWITCH are 0)
then automatic wake up is not available
The table is processed as set by field BRANCH to process: descriptor by descriptor, or
branch by the first descriptor in the current table 0 or the new table 1 (see
).
Table processing is started by a software trigger or external trigger input (see
and
). The active table and active table descriptor are indicated by
STATUS_REG1 (see
). By chaining table 0 and table 1 and updating the not
active table, infinite long conversion sequences can be created.
The ADC controller uses a shadow table that is mapped to DESCRIPTOR0/1 registers
and another table that is used to control the ADC. The complete shadow table is copied
when UPDATE_TABLE of any descriptor entry is set to 1. When writing new table entries
to DESCRIPTOR0 these registers read do not reflect the table used by the ADC
processing until UPDATE_TABLE has been set 1 again.
Table 1137.Descriptor table 0 registers (DESCRIPTOR0_[0:7], address 0x400F 0300
(DESCRIPTOR0_0) to 0x400F 031C (DESCRIPTOR0_7)) bit description
Bit
Symbol
Description
Reset
value
2:0
CHANNEL_NR
0: convert input 0
1: convert input 1
2: convert input 2
3: convert input 3
4: convert input 4
5: convert input 5
6,7: reserved
0x0
3
HALT
0: After this descriptor continue with the next descriptor.
1: halt after this descriptor is processed. Restart at a new
trigger.
0x0
4
INTERRUPT
1: Raise interrupt when ADC result is available
0x0
5
POWER_DOWN
1: Power down after this conversion.
0x1
7:6
BRANCH
00: Continue with next descriptor (wraps around after
top).
01: Branch to the first descriptor in this table.
10: Swap tables and branch to the first descriptor of the
new table.
11: reserved (do not store sample). Continue with next
descriptor (wraps around after top).
0x3
21:8
MATCH_VALUE
Evaluate this descriptor when descriptor timer value is
equal to match value.
0x90
23:22 THRESHOLD_SEL Indicates which threshold comparison level register set is
to be used:
00: no comparison,
01: THR_A.
10: THR_B.
11: Reserved
0x0