LM3S817 Datasheet, PDF (459/553 Pages) List of Unclassifed Manufacturers – Microcontroller

Stellaris^® LM3S817 Microcontroller
Figure 14-2. 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
14.2
Signal Description
Table 14-1 on page 459 lists the external signals of the PWM module module and describes 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 248) should be set to choose the PWM function. For more
information on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 229.
Table 14-1. PWM Signals (48QFP)
Pin Name
Pin Number Pin Type Buffer Type^a Description
Fault
34
I
TTL
PWM Fault.
PWM0
25
O
TTL
PWM 0. This signal is controlled by PWM Generator 0.
PWM1
26
O
TTL
PWM 1. This signal is controlled by PWM Generator 0.
PWM2
29
O
TTL
PWM 2. This signal is controlled by PWM Generator 1.
PWM3
30
O
TTL
PWM 3. This signal is controlled by PWM Generator 1.
PWM4
35
O
TTL
PWM 4. This signal is controlled by PWM Generator 2.
PWM5
36
O
TTL
PWM 5. This signal is controlled by PWM Generator 2.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
14.3 Functional Description
14.3.1
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
July 14, 2014
459
Texas Instruments-Production Data