LM3S1636_13 Datasheet, PDF (554/655 Pages) Texas Instruments – Stellaris Microcontroller

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Pulse Width Modulator (PWM)
Figure 16-2. PWM Module Block Diagram
PWM Generator Block
Interrupts /
Triggers
Control
PWMnCTL
Timer
zero
load
dir
PWMnLOAD
PWMnCOUNT
PWM Clock
Comparators
PWMnCMPA
PWMnCMPB
cmp A
cmp B
Interrupt and
Trigger
Generator
PWMnINTEN
PWMnRIS
PWMnISC
Signal
Generator
PWMnGENA
PWMnGENB
Fault
Condition
PWMnFLTSRC0
PWMnMINFLTPER
PWMnFLTSEN
PWMnFLTSTAT0
Fault(s)
PWMn_Fault
Dead-Band
Generator
PWMnDBCTL
PWMnDBRISE
PWMnDBFALL
PWMn_A
PWMn_B
16.2
Signal Description
Table 16-1 on page 554 list the external signals of the PWM module and describe the function of
each. The PWM controller signals are alternate functions for some GPIO signals and default to be
GPIO signals at reset. The column in the table below titled "Pin Assignment" lists the possible GPIO
pin placements for these PWM signals. The AFSEL bit in the GPIO Alternate Function Select
(GPIOAFSEL) register (page 301) should be set to choose the PWM function. For more information
on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 280.
Table 16-1. PWM Signals (100LQFP)
Pin Name
Pin Number Pin Type Buffer Type^a Description
Fault
99
I
TTL
PWM Fault.
PWM0
10
O
TTL
PWM 0. This signal is controlled by PWM Generator 0.
PWM1
11
O
TTL
PWM 1. This signal is controlled by PWM Generator 0.
PWM2
66
O
TTL
PWM 2. This signal is controlled by PWM Generator 1.
PWM3
67
O
TTL
PWM 3. This signal is controlled by PWM Generator 1.
PWM4
60
O
TTL
PWM 4. This signal is controlled by PWM Generator 2.
PWM5
59
O
TTL
PWM 5. This signal is controlled by PWM Generator 2.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
16.3 Functional Description
16.3.1
PWM Timer
The timer in each PWM generator runs in one of two modes: Count-Down mode or Count-Up/Down
mode. In Count-Down mode, the timer counts from the load value to zero, goes back to the load
value, and continues counting down. In Count-Up/Down mode, the timer counts from zero up to the
load value, back down to zero, back up to the load value, and so on. Generally, Count-Down mode
554
July 24, 2012
Texas Instruments-Production Data