Install Precompiled TensorFlow Lite 2.5 on Raspberry Pi

TensorFlow Lite is an open-source library that enables to run machine learning models and do inference on end devices, such as mobile or embedded devices. We cannot train a model using TensorFlow Lite. Before running model, we must convert a TensorFlow model to TensorFlow Lite model using TensorFlow Lite converter.

This tutorial shows how to install precompiled TensorFlow Lite 2.5 on Raspberry Pi.

Debian package

We have created Debian package (.deb) that contains precompiled TensorFlow Lite 2.5.0 binaries for Raspberry Pi 3 Model A+/B+ and Raspberry Pi 4 Model B. Binaries are compatible with Raspberry Pi OS Buster (32-bit). We have created a release on GitHub repository and uploaded tensorflow-lite.deb ​package.

TensorFlow Lite was built with the following features:

• NEON optimization
• VFPv4 optimization
• XNNPACK delegate
• Ruy matrix multiplication library
• MMAP-based allocation
• C and C++ APIs

Testing performed on Raspberry Pi 4 Model B (8 GB).

Install TensorFlow Lite

Use SSH to connect to Raspberry Pi. Execute the following command to download the .deb package from releases page of the repository:

wget https://github.com/prepkg/tensorflow-lite-raspberrypi/releases/latest/download/tensorflow-lite.deb

When the download is finished, install TensorFlow Lite:

sudo apt install -y ./tensorflow-lite.deb

You can remove .deb package because no longer needed:

rm -rf tensorflow-lite.deb

Testing TensorFlow Lite (C API)

Debian package contains a shared libraries of C and C++ APIs. First, we will test C API. Before starting, install GNU C compiler:

sudo apt install -y gcc

For testing, we need to have TensorFlow Lite model. You can read post how to convert TensorFlow 2 model to TensorFlow Lite model or you can download prepared model from Internet:

wget -O model.tflite https://www.dropbox.com/s/b1426ewx13idlr0/simple_linear_regression.tflite?dl=1

This model solves simple linear regression problem described in the post.

Create a main.c file:

nano main.c

Add the following code:

#include <stdio.h>
#include <tensorflow/lite/c/common.h>
#include <tensorflow/lite/c/c_api.h>

int main()
{
    int numThreads = 4;

    TfLiteModel *model = TfLiteModelCreateFromFile("model.tflite");

    TfLiteInterpreterOptions *options = TfLiteInterpreterOptionsCreate();
    TfLiteInterpreterOptionsSetNumThreads(options, numThreads);
    TfLiteInterpreter *interpreter = TfLiteInterpreterCreate(model, options);

    TfLiteInterpreterAllocateTensors(interpreter);

    float x[] = {15.0f};

    TfLiteTensor *inputTensor = TfLiteInterpreterGetInputTensor(interpreter, 0);
    TfLiteTensorCopyFromBuffer(inputTensor, x, sizeof(x));

    TfLiteInterpreterInvoke(interpreter);

    float y[1];

    const TfLiteTensor *outputTensor = TfLiteInterpreterGetOutputTensor(interpreter, 0);
    TfLiteTensorCopyToBuffer(outputTensor, y, sizeof(y));

    printf("%.4f\n", y[0]);

    TfLiteInterpreterDelete(interpreter);
    TfLiteInterpreterOptionsDelete(options);
    TfLiteModelDelete(model);

    return 0;
}

A code is used to predict value of y for a previously unknown value of x. Model was trained using the following relationship between variables: y = 2 * x + 1.

We load a model and initialize TensorFlow Lite interpreter. A value of x variable is copied into the buffer of the input tensor. We execute a model. A value from buffer of the output tensor is copied to y variable. Finally, we print result and release resources.

Compile a code

gcc main.c -o test -ltensorflowlite_c

Run a program:

./test

In this case, x is 15.0 and model returns that y is 31.0044. Result can verified:

y = 2 * x + 1 = 2 * 15 + 1 = 31

Testing TensorFlow Lite (C++ API)

C API can be used from C++ code. However, TensorFlow Lite has C++ API as well. Make sure you have installed GNU C++ compiler:

sudo apt install -y g++

Create a main.cpp file:

nano main.cpp

When a file is opened, add the following code:

#include <iostream>
#include <tensorflow/lite/interpreter.h>
#include <tensorflow/lite/kernels/register.h>

using namespace tflite;

int main()
{
    int numThreads = 4;

    std::unique_ptr<FlatBufferModel> model = FlatBufferModel::BuildFromFile("model.tflite");

    ops::builtin::BuiltinOpResolver resolver;
    std::unique_ptr<Interpreter> interpreter;
    InterpreterBuilder(*model, resolver)(&interpreter, numThreads);

    interpreter->AllocateTensors();

    float x[] = {15.0f};

    float *inputTensor = interpreter->typed_input_tensor<float>(0);
    memcpy(inputTensor, x, sizeof(x));

    interpreter->Invoke();

    float *y = interpreter->typed_output_tensor<float>(0);

    std::cout << y[0] << std::endl;

    return 0;
}

A code was implemented using C++ API and performs the same job as code implemented with C API.

Execute the following command to compile a code:

g++ main.cpp -o test -ltensorflow-lite -ldl

Run a program:

./test

Uninstall TensorFlow Lite

If you want to completely remove TensorFlow Lite, run the following command:

sudo apt purge --autoremove -y tensorflow-lite