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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
315 of 368
NXP Semiconductors
UM10375
Chapter 20: LPC13xx Analog-to-Digital Converter (ADC)
20.6.2 A/D Global Data Register (AD0GDR - 0x4001 C004)
The A/D Global Data Register contains the result of the most recent A/D conversion. This
includes the data, DONE, and Overrun flags, and the number of the A/D channel to which
the data relates.
0x4
Start conversion when the edge selected by bit 27 occurs on CT32B0_MAT0. Timer
match function does not need to be selected on the device pin.
0x5
Start conversion when the edge selected by bit 27 occurs on CT32B0_MAT1. Timer
match function does not need to be selected on the device pin.
0x6
Start conversion when the edge selected by bit 27 occurs on CT16B0_MAT0. Timer
match function does not need to be selected on the device pin.
0x7
Start conversion when the edge selected by bit 27 occurs on CT16B0_MAT1. Timer
match function does not need to be selected on the device pin.
27
EDGE
This bit is significant only when the START field contains 010-111. In these cases:
0
0
Start conversion on a rising edge on the selected CAP/MAT signal.
1
Start conversion on a falling edge on the selected CAP/MAT signal.
31:28 -
Reserved, user software should not write ones to reserved bits. The value read from a
reserved bit is not defined.
NA
Table 305: A/D Control Register (AD0CR - address 0x4001 C000) bit description
Bit
Symbol
Value Description
Reset
Value
Table 306: A/D Global Data Register (AD0GDR - address 0x4001 C004) bit description
Bit
Symbol
Description
Reset
Value
5:0
-
Reserved.
0
15:6
V_VREF
When DONE is 1, this field contains a binary fraction representing the
voltage on the ADn pin selected by the SEL field, divided by the voltage
on the V
DD
pin. Zero in the field indicates that the voltage on the ADn
pin was less than, equal to, or close to that on V
SS
, while 0x3FF
indicates that the voltage on ADn was close to, equal to, or greater than
that on V
REF
.
X
23:16 -
Reserved.
0
26:24 CHN
These bits contain the channel from which the V_VREF bits were
converted.
X
29:27 -
Reserved.
0
30
OVERR
UN
This bit is 1 in burst mode if the results of one or more conversions was
(were) lost and overwritten before the conversion that produced the
result in the V_VREF bits.
0
31
DONE
This bit is set to 1 when an A/D conversion completes. It is cleared
when this register is read and when the ADCR is written. If the ADCR is
written while a conversion is still in progress, this bit is set and a new
conversion is started.
0