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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
1330 of 1441
NXP Semiconductors
UM10503
Chapter 47: LPC43xx/LPC43Sxx 10-bit ADC0/1
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
47.6.1 A/D Control register
The A/D Control Register provides bits to select A/D channels to be converted, A/D timing,
A/D modes, and the A/D start trigger.
Table 1114. A/D Control register (CR - address 0x400E 3000 (ADC0) and 0x400E 4000 (ADC1)) bit description
Bit
Symbol
Value
Description
Reset
value
7:0
SEL
Selects which of the ADCn_[7:0] inputs are to be sampled and converted. Bit 0
selects ADCn_0, bit 1 selects pin ADCn_1,..., and bit 7 selects pin ADCn_7. In
software-controlled mode, only one of these bits should be 1. In hardware scan
mode, any value containing 1 to 8 ones is allowed. All zeroes is equivalent to
SEL = 0x01.
0
15:8
CLKDIV
The ADC clock is divided by the CLKDIV value plus one to produce the clock
for the A/D converter, which should be less than or equal to 4.5 MHz. Typically,
software should program the smallest value in this field that yields a clock of
4.5 MHz or slightly less, but in certain cases (such as a high-impedance analog
source) a slower clock may be desirable.
0
16
BURST
Controls Burst mode
0
0
Conversions are software controlled and require 11 clocks.
1
The AD converter does repeated conversions at the rate selected by the CLKS
field, scanning (if necessary) through the pins selected by 1s in the SEL field.
The first conversion after the start corresponds to the least-significant 1 in the
SEL field, then higher numbered 1 bits (pins) if applicable. Repeated
conversions can be terminated by clearing this bit, but the conversion that’s in
progress when this bit is cleared will be completed. The conversion result is
stored in the DR0 to DR7 registers, The GDR does not contain valid
conversion results in burst mode.
Important:
START bits must be 000 when BURST = 1 or conversions will not
start.
19:17 CLKS
This field selects the number of clocks used for each conversion in Burst mode
and the number of bits of accuracy of the result in the LS bits of ADDR,
between 11 clocks (10 bits) and 4 clocks (3 bits).
000
0x0
11 clocks / 10 bits
0x1
10 clocks / 9 bits
0x2
9 clocks / 8 bits
0x3
8 clocks / 7 bits
0x4
7 clocks / 6 bits
0x5
6 clocks / 5 bits
0x6
5 clocks / 4 bits
0x7
4 clocks / 3 bits
20
-
-
Reserved, user software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
-
21
PDN
Power mode
0
0
The A/D converter is in Power-down mode.
1
The A/D converter is operational.
23:22 -
-
Reserved, user software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
-