LM3S1G21 Datasheet, PDF (49/955 Pages) Texas Instruments – Stellaris® LM3S1G21 Microcontroller

Stellaris^® LM3S1G21 Microcontroller
1.3.6
1.3.6.1
■ Two means of port access: either Advanced High-Performance Bus (AHB) with better back-to-back
access performance, or the legacy Advanced Peripheral Bus (APB) for backwards-compatibility
with existing code
■ Fast toggle capable of a change every clock cycle for ports on AHB, every two clock cycles for
ports on APB
■ Programmable control for GPIO interrupts
– Interrupt generation masking
– Edge-triggered on rising, falling, or both
– Level-sensitive on High or Low values
■ Bit masking in both read and write operations through address lines
■ Can be used to initiate an ADC sample sequence
■ Pins configured as digital inputs are Schmitt-triggered
■ Programmable control for GPIO pad configuration
– Weak pull-up or pull-down resistors
– 2-mA, 4-mA, and 8-mA pad drive for digital communication; up to four pads can sink 18-mA
for high-current applications
– Slew rate control for the 8-mA drive
– Open drain enables
– Digital input enables
Analog
The LM3S1G21 microcontroller provides analog functions integrated into the device, including:
■ 12-bit Analog-to-Digital Converter (ADC) with eight analog input channels and a sample rate of
one million samples/second
■ Two analog comparators
■ Eight digital comparators
■ On-chip voltage regulator
The following provides more detail on these analog functions.
ADC (see page 602)
An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a
discrete digital number. The Stellaris ADC module features 12-bit conversion resolution and supports
eight input channels plus an internal temperature sensor. Four buffered sample sequencers allow
rapid sampling of up to eight analog input sources without controller intervention. Each sample
sequencer provides flexible programming with fully configurable input source, trigger events, interrupt
January 22, 2012
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Texas Instruments-Production Data