LM3S2776 Datasheet, PDF (454/785 Pages) Texas Instruments – Stellaris® LM3S2776 Microcontroller

Analog-to-Digital Converter (ADC)
Figure 12-1. ADC Module Block Diagram
Trigger Events
Comparator
GPIO (PB4)
Timer
SS3
PWM
Comparator
GPIO (PB4)
Timer
SS2
PWM
Comparator
GPIO (PB4)
Timer
SS1
PWM
Comparator
GPIO (PB4)
Timer
SS0
PWM
SS0 Interrupt
SS1 Interrupt
SS2 Interrupt
SS3 Interrupt
ADCEMUX
ADCPSSI
Control/Status
ADCACTSS
ADCOSTAT
ADCUSTAT
ADCSSPRI
Interrupt Control
ADCIM
ADCRIS
ADCISC
Sample
Sequencer 0
ADCSSMUX0
ADCSSCTL0
ADCSSFSTAT0
Sample
Sequencer 1
ADCSSMUX1
ADCSSCTL1
ADCSSFSTAT1
Sample
Sequencer 2
ADCSSMUX2
ADCSSCTL2
ADCSSFSTAT2
Sample
Sequencer 3
ADCSSMUX3
ADCSSCTL3
ADCSSFSTAT3
Analog-to-Digital
Converter
Hardware Averager
ADCSAC
FIFO Block
ADCSSFIFO0
ADCSSFIFO1
ADCSSFIFO2
ADCSSFIFO3
Analog Inputs
12.2
Signal Description
Table 12-1 on page 454 lists the external signals of the ADC module and describes the function of
each. The signals are analog functions for some GPIO signals. The column in the table below titled
"Pin Assignment" lists the GPIO pin placement for the ADC signals. The AINx analog signals are
not 5-V tolerant and go through an isolation circuit before reaching their circuitry. These signals are
configured by clearing the corresponding DEN bit in the GPIO Digital Enable (GPIODEN) register
and setting the corresponding AMSEL bit in the GPIO Analog Mode Select (GPIOAMSEL) register.
For more information on configuring GPIOs, see “General-Purpose Input/Outputs
(GPIOs)” on page 348.
Table 12-1. ADC Signals (64LQFP)
Pin Name
Pin Number Pin Type Buffer Type^a Description
ADC0
1
I
Analog Analog-to-digital converter input 0.
ADC1
2
I
Analog Analog-to-digital converter input 1.
ADC2
5
I
Analog Analog-to-digital converter input 2.
ADC3
6
I
Analog Analog-to-digital converter input 3.
ADC4
64
I
Analog Analog-to-digital converter input 4.
ADC5
63
I
Analog Analog-to-digital converter input 5.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
12.3
Functional Description
The Stellaris ADC collects sample data by using a programmable sequence-based approach instead
of the traditional single or double-sampling approaches found on many ADC modules. Each sample
sequence is a fully programmed series of consecutive (back-to-back) samples, allowing the ADC
to collect data from multiple input sources without having to be re-configured or serviced by the
454
November 17, 2011
Texas Instruments-Production Data