UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
1165 of 1269
NXP Semiconductors
UM10503
Chapter 45: LPC43xx DAC
45.5 Register description
45.5.1 D/A converter register
This read/write register includes the digital value to be converted to an analog output
value and a bit that trades off performance vs. power.
45.5.2 D/A Converter Control register
This read/write register enables the DMA operation and controls the DMA timer.
Table 1016.DAC pin description
Pin
Type
Description
DAC
Output
Analog Output. The voltage on this pin (with respect to V
SSA
) is
VALUE/1024
VDDA as written to the DAC CR register
).The DAC pin is shared with the channel 0 input pin of
ADC0 and ADC1. The settling time of the DAC output can be
controlled by the BIAS bit in the DAC CR register.
VDDA
Power
Analog power and voltage reference. This pin provides a voltage
reference level VREF for the D/A converter.
VSSA
-
Ground.
Table 1017.Register overview: DAC (base address 0x400E 1000)
Name
Access
Address
offset
Description
Reset
value
Reference
CR
R/W
0x000
DAC register. Holds the conversion
data.
0
CTRL
R/W
0x004
DAC control register.
0
CNTVAL
R/W
0x008
DAC counter value register.
0
Table 1018:D/A Converter register (CR - address 0x400E 1000) bit description
Bit
Symbol Value
Description
Reset
value
5:0
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-
15:6
VALUE
Once this field is written with a new VALUE, the voltage on the
DAC pin (with respect to V
SSA
) is VALUE/1024 x VDDA. The
value of the DAC output pin is valid after the selected settling
time (see the BIAS bit in this register) has expired.
0
16
BIAS
Settling time
0
0
Shorter settling times and higher power consumption; allows
for a maximum update rate of 1 MHz.
1
Longer settling times and lower power consumption; allows for
a maximum update rate of 400 kHz.
31:17 -
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-