LM3S301 Luminary Micro, Inc, LM3S301 Datasheet - Page 201

• Manufacturer Part Number: LM3S301
• Description: Lm3s301 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

11.3
11.3.1
11.3.2
July 5, 2006
Figure 11-2. Internal Temperature Sensor Characteristic
Initialization and Configuration
In order for the ADC module to be used, the PLL must be enabled and using a supported crystal
frequency (see the RCC register on page 79). Using unsupported frequencies can cause faulty
operation in the ADC module.
Module Initialization
Initialization of the ADC module is a simple process with very few steps. The main steps include
enabling the clock to the ADC and reconfiguring the Sample Sequencer priorities (if needed).
The initialization sequence for the ADC is as follows:
1.
2.
Sample Sequencer Configuration
Configuration of the Sample Sequencers is slightly more complex than the module initialization
since each sample sequence is completely programmable.
The configuration for each Sample Sequencer should be as follows:
1.
2.
3.
4.
5.
6.
Enable the ADC clock by writing a value of 0x00010000 to the RCGC1 register in the System
Control Module.
If required by the application, reconfigure the Sample Sequencer priorities in the ADCSSPRI
register. The default configuration has Sample Sequencer 0 with the highest priority, and
Sample Sequencer 3 as the lowest priority.
Ensure that the Sample Sequencer is disabled by writing a 0 to the corresponding ASEN bit in
the ADCACTSS register. Programming of the Sample Sequencers is allowed without having
them enabled. Disabling the Sequencer during programming prevents erroneous execution if
a trigger event were to occur during the configuration process.
Configure the trigger event for the Sample Sequencer in the ADCEMUX register.
For each sample in the sample sequence, configure the corresponding input source in the
ADCSSMUXn register.
For each sample in the sample sequence, configure the sample control bits in the
corresponding nibble in the ADCSSCTLn register. When programming the last nibble, ensure
that the END bit is set. Failure to set the END bit causes unpredictable behavior.
If interrupts are to be used, write a 1 to the corresponding MASK bit in the ADCIM register.
Enable the Sample Sequencer logic by writing a 1 to the corresponding ASEN bit in the
ADCACTSS register.
Preliminary
LM3S301 Data Sheet
201