LM3S308 Luminary Micro, Inc, LM3S308 Datasheet - Page 369

• Manufacturer Part Number: LM3S308
• Description: Lm3s308 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

15.3
June 04, 2008
to develop specific internal reference values, to compare an external voltage against a particular
voltage generated internally.
Figure 15-3. Comparator Internal Reference Structure
VREF
Table 15-2. Internal Reference Voltage and ACREFCTL Field Values
Initialization and Configuration
The following example shows how to configure an analog comparator to read back its output value
from an internal register.
1.
2.
ACREFCTL Register
EN Bit Value
RNG
EN
EN=0
EN=1
Enable the analog comparator 0 clock by writing a value of 0x0010.0000 to the RCGC1 register
in the System Control module.
In the GPIO module, enable the GPIO port/pin associated with C0- as a GPIO input.
AVDD
RNG Bit Value
RNG=X
RNG=0
RNG=1
8R
Output Reference Voltage Based on VREF Field Value
0 V (GND) for any value of VREF; however, it is recommended that RNG=1 and VREF=0
for the least noisy ground reference.
Total resistance in ladder is 31 R.
The range of internal reference in this mode is 0.85-2.448 V.
Total resistance in ladder is 23 R.
The range of internal reference for this mode is 0-2.152 V.
15
R
14
Preliminary
Decoder
R
1
R
0
8R
internal
reference
LM3S308 Microcontroller
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