UM10147_2
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 02 — 28 April 2008
27 of 134
NXP Semiconductors
UM10147
P89LPC952/954 User manual
•
Three conversion start modes
–
Timer triggered start
–
Start immediately
–
Edge triggered
•
10-bit conversion time of
4 μ
s at an A/D clock of 9 MHz
•
Interrupt or polled operation
•
High and low boundary limits interrupt
•
Clock divider
•
Power down mode
3.2.1 A/D operating modes
3.2.1.1
Fixed channel, single conversion mode
A single input channel can be selected for conversion. A single conversion will be
performed and the result placed in the result register pair which corresponds to the
selected input channel (see
). An interrupt, if enabled, will be generated after the
conversion completes. The input channel is selected in the ADINS register. This mode is
selected by setting the SCAN0 bit in the ADMODA register.
3.2.1.2
Fixed channel, continuous conversion mode
A single input channel can be selected for continuous conversion. The results of the
conversions will be sequentially placed in the eight result register pairs (see
). The
user may select whether an interrupt can be generated after every four or every eight
Fig 8.
ADC block diagram.
+
–
comp
DAC0
SAR
8
INPUT
MUX
CONTROL
LOGIC
CCLK
002aab103
Table 7.
Input channels and result registers for fixed channel single, auto scan single, and
auto scan continuous conversion modes
Result register
Input channel
Result register
Input channel
AD0DAT0R/L
AD00
AD0DAT4R/L
AD04
AD0DAT1R/L
AD01
AD0DAT5R/L
AD05
AD0DAT2R/L
AD02
AD0DAT6R/L
AD06
AD0DAT3R/L
AD03
AD0DAT7R/L
AD07