The easiest way to install it is to run FriendlyELEC's script.

• S5P6818 NanoPC T3/T3 Plus
  NanoPi Fire3
  Smart6818
  NanoPi M3
• S5P4418 NanoPC T2 Plus
  NanoPi Fire2a
  Smart4418
  NanoPi S2
  NanoPi M2/M2a

Note: Requires latest version of FriendlyCore firmware (Version after 20191126),
Please download the latest FriendlyCore Image file from the following URL: http://download.friendlyarm.com

git clone https://github.com/friendlyarm/install-caffe-on-friendlycore
cd install-caffe-on-friendlycore
sudo ./install-caffe.sh

After successful installation, you will see the following text:

[  PASSED  ] 1058 tests.

Built Complete
--------------------------------------------
You may run a quick timing test use the following command:
cd /home/pi/install-caffe-on-friendlycore/caffe
sudo ./build/tools/caffe time --model=models/bvlc_alexnet/deploy.prototxt