Basic usage for Micro Controllers

MACE Micro is a lightweight neural network inference engine for MCUs. At now we support Cortex-M MCUs. You can get our projects from GitHub.

Get MACE Micro Projects

MACE Micro is a sub project of MACE, so you can get it from MACE.

git clone
# Inits submodules by yourself
cd mace && git submodule update --init micro && cd ..

Environment Requirements

On a ubuntu18.04/20.04 PC, do the following steps.

apt-get update
apt-get install -y wget

apt-get install -y g++
# Required for Cortex-M MCUs
apt-get install -y gcc-arm-none-eabi
apt-get install -y python3 python3-pip

python3 -m pip install jinja2 pyyaml sh numpy six filelock
# Installs cmake above 3.13.0
chmod +x && ./ --skip-license --prefix=/usr

python3 -m pip install -U pip
# The Tensorflow version depends on your model
# The Tensroflow 1.x frozen model and Tensorflow 2.x Keras model are both supported
python3 -m pip install tensorflow==2.3.0
python3 -m pip install tensorflow_model_optimization

You also can use a docker as the environment.

cd mace/docker/mace-micro-dev
docker build . -f mace-micro-dev.dockerfile --tag mace-micro-dev
cd ../../..
# Maps your workspace to docker container
docker run -ti -v $(pwd):/workspace/ -w /workspace  mace-micro-dev

Convert a model to c++ code

Here we use a pre-trained model of the MNIST database,

cd mace
# Converts a tensorflow 2.x keras model, you need install python3 and tensorflow==2.x additional
python3 tools/python/ --config=micro/pretrained_models/keras/mnist/mnist.yml --enable_micro

Model config file

The following is a completed model config file,

library_name: mnist
target_abis: [host]
model_graph_format: file
model_data_format: file
    platform: keras
    model_sha256_checksum: 0ff90446134c41fb5e0524484cd9d7452282d3825f13b839c364a58abd0490ee
      - input_tensors:
          - conv2d_input:0
          - 1,28,28,1
          - 0,1
          - quant_dense_1/Softmax:0
          - 1,10
    runtime: cpu
    quantize: 1
    quantize_schema: int8
      backend: cmsis # Micro will use CMSIS_5 NN modules

For the bfloat16 model,

data_type: bf16_fp32

For the int8 model,

quantize: 1
quantize_schema: int8
# Required when your model has not quantize info
quantize_range_file: range_file_path

Build MACE Micro and models libraries

Here, we build the MACE Micro engine and models to libraries on a linux host machine. The CMake build parameters depends on your model config file.

For float32 model,


For bfloat16 model,

./micro/tools/cmake/ -DMACE_MICRO_ENABLE_BFLOAT16=ON


You can only use either float32 or bfloat16

For int8 model,

./micro/tools/cmake/ -DMACE_MICRO_ENABLE_CMSIS=ON

Use libraries directly

With these steps, we can find necessary libraries and headers in the "build/micro/host/install" directory, you can use the libraries directly.

# Builds example
g++ micro/examples/classifier/ -DMICRO_MODEL_NAME=mnist -DMICRO_DATA_NAME=mnist  -I build/micro/host/install/include/ -I micro/examples -L build/micro/host/install/lib/ -lmodel_mnist -lmicro -o mnist
# Runs the mnist example

Code example

The following code is the mnist example source files, which the main steps is annotated

#include "data/mnist.h"

#include <cstdio>

// Include MACE Micro header
#include "micro.h"

namespace micro {
namespace mnist {

// We use forward declaration to avoid include the special engine header
MaceStatus GetMicroEngineSingleton(MaceMicroEngine **engine);

}  // namespace micro

int main() {
  // Step 1, get the mnist micro engine
  micro::MaceMicroEngine *micro_engine = NULL;
  micro::MaceStatus status =

  // Step 2, set input data
  static float *input_data = data_mnist_4;
  int32_t input_dims[4] = {1, 28, 28, 1};
  micro_engine->RegisterInputData(0, input_data, input_dims);

  // Step3, run the inference

  // Step 4, get output data
  float *output_buffer = NULL;
  const int32_t *output_dims = NULL;
  uint32_t dim_size = 0;
      0, reinterpret_cast<void **>(&output_buffer), &output_dims, &dim_size);

  for (int32_t i = 0; i < output_dims[1]; ++i) {
    printf("%d: %f\n", i, output_buffer[i]);

  return 0;

For more examples, goto the directory "micro/examples"


We deploy a HAR-CNN int8 model on the NUCLEO-F767ZI(Cortex-M7) board. Each inference of HAR CNN model takes 12 ms.