Generate square wave on the specified output pin
Simulink Coder Support Package for NXP FRDM-KL25Z Board/FRDM-KL25Z
The PWM Output block generates square-wave pulses
and outputs to the specified pin on the board. You can provide a value
between 0–100 as the block input. The input value that you
provide controls the duty cycle of the pulse waveform. An input value
0 produces a 0% duty cycle and an input value
100 produces a 100% duty cycle.
Port_1— Duty cycle value
The range of valid input values is
The input controls the duty cycle (width of the square wave) of the
An input value of
0 produces a 0% duty cycle
and an input value of
100 produces a 100% duty
cycle. Any out-of-range values, such as
at the block input port has the same effect as the maximum or minimum
Pin— Output pin at which the block generates the square-wave pulse waveform
PTA5 (D5)(default) |
To view the pin mapping on the board, click View Pin Map. On the board, each PWM pin is connected to either of the three timers, TPM0 (Timer PWM Module), TPM1, or TPM2. To learn about the Timer Channel Pin combination, see the Timer to Pin Mapping table in the Timer/PWM module parameter description section.
Timer/PWM module— Timers that generate the PWM signal
The board has three timers, TPM0, TPM1, and TPM2. Each PWM pin
is connected to one of these three timers. When you select a pin in
the Pin list, this parameter is populated with
the timer to which the pin is connected. For example, if you select
PTA1 (D0) pin, this parameter is set
The following table shows timer to pin mapping.
In your model, if you have more than one instance of the PWM Output block, use a different Timer Channel combination for every block instance. Otherwise, you receive an error message indicating you to use GPIO Pins from different Timer Channel combination for all the block instances.
For example, suppose that in one PWM Output block
instance you select the
PTC3 pin to generate
the output. The
PTC3 pin is connected to
the CH2 channel of the TPM0 timer. When selecting a pin for the other
instances of the PWM Output block, select a pin that
belongs to a timer channel combination other than TPM0 CH2.
This parameter appears dimmed.
Initial duty cycle (0 - 100)— Initial duty cycle
integer between 0 and 100
When initializing, the block sets its duty cycle to the value that you specify in this parameter.
This example shows how to use the PWM Output block
to control the brightness of the blue LED connected to the
on the board.
Connect the FRDM-KL25Z hardware to your computer.
In the Simulink® Editor, open a new model window. From the Library Browser, copy a Constant block and a PWM Output block and connect them.
Set the value of the Constant block
50. This value represents the duty cycle of
the output square wave in percentage.
In the Block Parameter dialog box, set the Pin to
the Initial duty cycle to
In the Simulink Editor, select Simulation > Model Configuration Parameters.
In the Configuration Parameters dialog box, click Hardware Implementation.
Set the Hardware board parameter to NXP FRDM-KL25Z.
To set the frequency of the output signal, identify
the timer to which the
D13 pin is connected.
To identify the timer, in the Block Parameter dialog box, click View
Pin Map. In the pin map, search for the
and the timer name next to it. The
is connected to the
In the Configuration Parameters dialog box, set the TPM0
Frequency (in Hz) to
50. Using the frequency
value, the block calculates the period of the square wave.
Period = 1/50 = 0.02 seconds
When you build the model and load it on the hardware, the PWM Output block generates square-wave pulses with the pulse width of (50* 0.02)/100 = 0.01 seconds. The blue LED turns on for 0.01 seconds, and then it turns off for the next 0.01 seconds. You can blink an LED on and off quickly to control its brightness with the PWM Output block.