LM3S5C36 Datasheet, PDF (883/1068 Pages) Texas Instruments – Stellaris® LM3S5C36 Microcontroller

Stellaris^® LM3S5C36 Microcontroller
signals at reset. The column in the table below titled "Pin Mux/Pin Assignment" lists the possible
GPIO pin placements for these PWM signals. The AFSEL bit in the GPIO Alternate Function Select
(GPIOAFSEL) register (page 432) should be set to choose the PWM function. The number in
parentheses is the encoding that must be programmed into the PMCn field in the GPIO Port Control
(GPIOPCTL) register (page 449) to assign the PWM signal to the specified GPIO port pin. For more
information on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 412.
Table 19-1. PWM Signals (64LQFP)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
Fault0
5
PE1 (3)
I
8
PE4 (4)
27
PB3 (2)
TTL
PWM Fault 0.
Fault1
56
PB6 (4)
I
TTL
PWM Fault 1.
Fault2
14
PC5 (4)
I
TTL
PWM Fault 2.
Fault3
27
PB3 (4)
I
TTL
PWM Fault 3.
PWM0
25
PA6 (4)
O
61
PD0 (1)
TTL
PWM 0. This signal is controlled by PWM Generator
0.
PWM1
26
PA7 (4)
O
62
PD1 (1)
TTL
PWM 1. This signal is controlled by PWM Generator
0.
PWM2
41
PB0 (2)
O
63
PD2 (3)
TTL
PWM 2. This signal is controlled by PWM Generator
1.
PWM3
42
PB1 (2)
O
64
PD3 (3)
TTL
PWM 3. This signal is controlled by PWM Generator
1.
PWM4
6
PE0 (1)
O
19
PA2 (4)
25
PA6 (5)
TTL
PWM 4. This signal is controlled by PWM Generator
2.
PWM5
5
PE1 (1)
O
20
PA3 (4)
26
PA7 (5)
TTL
PWM 5. This signal is controlled by PWM Generator
2.
PWM6
11
PC4 (4)
O
21
PA4 (4)
TTL
PWM 6. This signal is controlled by PWM Generator
3.
PWM7
15
PC6 (4)
O
22
PA5 (4)
TTL
PWM 7. This signal is controlled by PWM Generator
3.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
19.3 Functional Description
19.3.1
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
is used for generating left- or right-aligned PWM signals, while the Count-Up/Down mode is used
for generating center-aligned PWM signals.
The timers output three signals that are used in the PWM generation process: the direction signal
(this is always Low in Count-Down mode, but alternates between Low and High in Count-Up/Down
mode), a single-clock-cycle-width High pulse when the counter is zero, and a single-clock-cycle-width
High pulse when the counter is equal to the load value. Note that in Count-Down mode, the zero
January 23, 2012
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