SD Card File Read
Read data from an SD card
Add-On Required: This feature requires the Simulink Support Package for Arduino Hardware add-on.
Libraries:
Simulink Support Package for Arduino Hardware /
Common
Description
The SD Card File Read block reads data from files stored in an SD card that is connected to the hardware. The hardware communicates with the SD card over Serial Peripheral Interface (SPI). Specify the SD Card SPI SS pin for communication in the Configuration Parameters dialog box.
If you simulate a model that contains the SD Card Read block without connecting the hardware, the block outputs zeros. For more information, see Block Produces Zeros or Does Nothing in Simulation.
Click View pin map to open the Arduino Pin Mapping table.
To know how to assign pins for the block, see Pin Mapping for Arduino Timer Independent Blocks.
Note
You can now deploy a Simulink® model containing the SD Card File Read block on your Arduino® compatible ESP32 WROOM and ESP32 WROVER boards.
Ports
Input
Port_1 — Index to read data
scalar
The port accepts the index to read data. For raw and ASCII files, the block starts reading data from the specified index. For audio files, the block starts reading data from the location that is calculated using the specified index, excluding the Waveform Audio File Format (WAV) header.
Dependencies
To enable this port, select the Enable reading from index parameter.
Data Types: uint8
Output
Data — Audio data from SD card
M-by-N matrix
The block outputs the data read from the SD card. The format of the output depends on the File type parameter. If you select the File type as:
Raw
–– The block outputs the data inuint8
format.ASCII
–– By default, the block outputs the data inuint8
format. If you select the Enable Delimiter parameter, the block outputs the data in the Data type format.Audio (wav)
–– The block outputs the audio data as an M-by-N matrix, where M is the Frame size, and N is the Number of Channels supported by the audio.
The block outputs zeroes when it encounters the end of the file (EOF).
Data Types: double
| single
| int8
| uint8
| int16
| uint16
| int32
| uint32
| Boolean
Status — Status of the read operation
scalar
The block outputs the status of read operation as a
uint8
value. Each value corresponds to a data
transfer status.
Status Value | Status Description |
---|---|
0 | SUCCESS |
1 | FILE CANNOT BE OPENED |
2 | NOT A WAVE FILE |
3 | BLOCK MASK DATA MISMATCH FOR
AUDIO |
4 | INDEX VALUE EXCEEDS FILE
LENGTH |
5 | FILE HAS CHARACTERS OTHER THAN (0-9,
Period, and Delimiter) |
6 | END OF FILE |
Data Types: uint8
Parameters
SPI module — SPI communication module
0
(default) | scalar
Specify the SPI module on the Arduino hardware to communicate with SPI peripherals. For more information on Arduino pin mapping and modules that hardware boards support, see Pin Mapping for Arduino Timer Independent Blocks.
File type — Read format of data file
Raw
(default) | ASCII
| Audio(wav)
Specify the format in which the block reads the file.
File name — Name of audio file
testaudio.wav
(default)
Specify the path and name of the file from which the block reads data. For
example, to read the sample.wav
file that is located
inside the TestAudio
folder of the SD card, specify the
File name as
/TestAudio/sample.wav
Number of times to read file — Number of times to read the audio file
Inf
(default) | positive integer
Specify the number of times the block reads the file from beginning. To
read the file until you stop the simulation, specify the Number of
times to read file as Inf
.
Enable reading from index — Enable reading from given index
off (default) | on
When you select the Enable reading from index parameter, the block configures an input port. Specify an index at this port.
For raw and ASCII files, the block starts reading data from the specified index. For audio files, the block starts reading data from the location that is calculated using the specified index, excluding the WAV header.
Enable Delimiter — Option to read data using delimiters
off (default) | on
off
–– The block reads data and outputs it inuint8
format.on
–– At each sample time, the block reads data until it encounters the next delimiter, specified in the Delimitter parameter. The block outputs the data in the Data type format, omitting the delimiter at the end. The block continues to read the data until the EOF is encountered.
Dependencies
To enable this parameter, set File type to
ASCII
.
Delimitter — Delimiter to read data
, (default)
Specify the delimiter to read the data. At each sample time, the block reads data until it encounters the next delimiter. The block outputs the data in the Data type format, omitting the delimiter at the end. The block continues to read the data until the EOF is encountered.
Dependencies
To enable this parameter, select the Enable Delimiter parameter.
Sample time — Time interval to read data
-1
(default) | positive integer
For raw and ASCII files, specify how often the block reads data from the
SD card. When you set this parameter to -1
, Simulink determines the best sample time for the block based on the
block context within the model.
For audio (wav) files, the block calculates the sample time (Ts) from the frame size (N) and sampling rate (Fs) of the selected audio file.
Ts = N / Fs
For example, if N is 4410 samples and Fs is 44,100 Hz, the block sample time is 4410/44,100 = 0.1 seconds.
N is the value that you specify in the Frame size parameter. Fs is the value that you specify in the Sample rate (Hz) parameter.
Sample rate (Hz) — Number of samples per frame of audio data
44100
(default) | positive integer between 1
and
48000
Specify the sample rate used by the audio input device to read audio data, in Hz. Larger frame sizes may result in a delay in your audio input. Ensure that the audio sampling frequency matches the input sampling frequency to avoid any issues in the output.
Tip
To find the sample rate of the specified audio file, use the
audioinfo
command in the MATLAB® Command Window. Copy the sample rate from the
SampleRate
property of the
audioinfo
command and paste the copied rate
to the Sample rate (Hz) parameter.
Dependencies
To enable this parameter, set File type to
Audio (wav)
.
Number of Channels — Number of channels supported
1
(default) | 2
Specify if the audio file is mono or stereo. If the audio file is mono,
set this parameter value as 1
. If the audio file is
stereo, set this parameter value as 2
.
Tip
To find the number of channels that the specified audio file supports,
use the audioinfo
command in the MATLAB Command Window. Set the Number of
Channels parameter to the value displayed in the
NumChannels
property of the
audioinfo
command.
Dependencies
To enable this parameter, set File type to
Audio (wav)
.
Bits per sample — Number of bits
8
(default) | 16
Specify the number of bits in each sample of audio.
Tip
To find the bits per sample for the specified audio file, use the
audioinfo
command in the MATLAB Command Window. Set the Bits per
sample parameter to the value displayed in the
BitsPerSample
property of the
audioinfo
command.
Dependencies
To enable this parameter, set File type to
Audio (wav)
.
Frame Size — Number of samples per frame of audio data
100
(default) | positive integer between 1
and
16384
Specify the number of samples in a frame. Larger frame sizes may result in a delay in your audio output.
Dependencies
To enable this parameter, set File type to
Audio (wav)
.
Version History
Introduced in R2019b
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