Encoder
Libraries:
Simulink Support Package for Raspberry Pi Hardware /
Basic
Description
The Encoder block outputs the tick count from a quadrature encoder on a rotating motor connected to a Raspberry Pi® hardware board. Every increment in the tick count of the encoder indicates that the motor is rotating clockwise. Every decrement in the tick count of the encoder indicates that the motor is rotating counterclockwise. The total tick count represents the incremental position of the rotating motor.
You can reset the encoder readings from the block using the Reset mode parameter in the block parameters dialog box.
When simulating without hardware, this block outputs zeros. For more information, see Block Produces Zeros or Does Nothing in Simulation.
Ports
Input
Port_1 — External signal to reset encoder reading
scalar
Use this input port to reset the Encoder block tick counter.
When the value of the signal at the input port is 0
, the block
outputs the total tick count read from the encoder. In this case, the block output is
the same as in the No reset
mode. When the value of the
signal at the input port is a nonzero value, the block outputs the number of ticks
read from the encoder at the given sample time. In this case, the block output is the
same as in the Reset at each Sample time
mode.
Dependencies
To enable this port, set Reset mode to Reset
by external signal
.
Data Types: single
| double
| int8
| int16
| int32
| uint8
| uint16
| uint32
| Boolean
Output
Tick — Incremental position of rotating motor
scalar
The block outputs the relative change in the position of the rotating motor in
ticks. You can find out the direction of rotation of the motor based on the previous
and current tick counts and the Reset mode selected. For example, in the No reset
mode, with a previous tick count of 30
and current tick count of
20
, the motor is moving in a counterclockwise direction.
Data Types: int16
Parameters
Board — Raspberry Pi hardware board
Pi 4 Model B
(default) | Model B Rev1
| Model B Rev2
| Model B+
| Pi 2 Model B
| Pi 3 Model B
| Pi 3 Model B+
| Pi Zero W
| Compute Module 4
| Pi Zero 2 W
| Pi 5 Model
Select your Raspberry Pi hardware board. You can find this information on the target hardware, product packaging, or product documentation.
Input A — GPIO pin of hardware
GPIO 20 (default) | GPIO pin 4 – 19 or GPIO pin 21 – 27
Select the GPIO pin on the Raspberry Pi hardware board to which the output A of the encoder is connected.
Input B — GPIO pin of hardware
GPIO 21 (default) | GPIO pin 4 – 19 or GPIO pin 21 – 27
Select the GPIO pin on the Raspberry Pi hardware board to which the output B of the encoder is connected.
Reset mode — Reset block output
No reset
(default) | Reset at each Sample time
| Reset at external signal
The block supports three reset modes.
No reset
— The block outputs the total tick count read from the encoder.Reset at each Sample time
— The block outputs the number of ticks read from the encoder at the given sample time.Reset by external signal
— When you set the parameter to this mode, an input port becomes available. In this mode, when the value of the signal at the input port is0
, the block output is the same as in theNo reset
mode. When the value of the signal at the input port is a nonzero value, the block output is the same as in theReset at each sample time
mode.
Assume that the encoder wheel connected to the hardware has 90 slots, which means that the encoder tick count is 1 for every 4 degrees of rotation. Assume that the block sample time is 1 second and the tick count at time instant T = 0 is 0. This table shows the tick counts that the block outputs in the three modes.
Between T = 0 and T = 1, assume that the encoder rotates 20 degree clockwise. The output in each mode is:
No reset
— The output is 20 / 4 = 5Reset at each sample time
— Assume that the encoder has rotated 20 degrees at the given sample time, so the output is 20 / 4 = 5Reset by external signal
— Assume that the value of the external signal is 0, so the count is calculated as in theNo reset
mode, and the output is 20 / 4 = 5
Between T = 1 and T = 2, assume that the encoder rotates 40 degrees clockwise. The output in each mode is:
No reset
— In this mode, the block outputs at any time instant is the sum of the previous count and the current count, so the output is 5 + 40 / 4 = 15Reset at each sample time
— Assume that the encoder has rotated 40 degrees at the given sample time, so the output is 40 / 4 = 10Reset by external signal
— Assume that the value of the external signal is 0, so the count is calculated as in theNo reset
mode, and the output is 5 + 40 / 4 = 15
Between T = 3 and T = 4, assume that the encoder rotates 20 degrees counterclockwise. The output in each mode is:
No reset
— In this mode, the block output at any time instant is the sum of the previous count and the current count, so the output is 30 – 20 / 4 = 25Reset at each sample time
— Assume that the encoder has rotated 20 degree counterclockwise at the given sample time, so the output is – 20 / 4 = – 5Reset by external signal
— Assume that the value of the external signal is a nonzero value, so the count is calculated as in theReset at each sample time
mode, and the output is – 20 / 4 = – 5
Sample time — Time at which block reads data from encoder
-1
(default) | scalar
Enter the time interval in seconds at which the block reads values from the encoder.
Version History
Introduced in R2021a
MATLAB 명령
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명령을 실행하려면 MATLAB 명령 창에 입력하십시오. 웹 브라우저는 MATLAB 명령을 지원하지 않습니다.
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