(r3) CompilingNopMicroPython < IoT_Course

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---+ Compiling !Micropython
---++ Forcing the correct module versions

When trying to compile the ESP32 port of !MicroPython on an Ubuntu-20.04 system I see the following error:

<img alt="compileError.png" height="347" src="%ATTACHURL%/compileError.png" title="compileError.png" width="804" />

As the message states we are running a version of pyparsing which is too recent for the ESP_IDF development environment and we must create a virtual environment for Python3 with an older version the pyparsing.

This is how I did it:

First I created a directory ~/pythonEnvironments in my home directory. <br />Then I created a virtual environment mp_env for !MicroPython compilation:
<verbatim>python3 -m venv mp_env</verbatim>

Once the environment is created you can _activate_ it:
<verbatim>source mp_env/bin/activate</verbatim>

In your new environment you can use pip to load the modules you need with the correct version numbers:
<verbatim>pip3 install pyparsing==2.3.1
pip3 install pyserial</verbatim>

When this is accomplished compilation of !MicroPython works as expected:

<img alt="virtualEnv.png" height="522" src="%ATTACHURL%/virtualEnv.png" title="virtualEnv.png" width="1167" />

As soon as you are done you can deactivate the environment and return to the standard Python environment with the _deactivate_ command.
---++ Freezing modules into the !MicroPython binary

We want to give students easy access to drivers for the sensors we use during the course. If we compile and freeze these modules into the !MicroPython binary, then these module are available for import without the necessity to upload them to the ESP32 before use. in addition this method frees valuable RAM space, a resource that is very scarce on the machine.

Freezing of !MicroPython modules into the binary is pretty easy: We must simply copy the Python code into the ports/esp32/modules directory of the !MicroPython source before compilation. Here is the list of additional modules that are currently included:

<img alt="modules.png" height="92" src="%ATTACHURL%/modules.png" title="modules.png" width="960" />

---++ Including user C modules

Sometimes it may be needed to write modules in C, which can be called by !MicroPython. A typical example is the readout of the DHT11 when we want to get access to the raw data sent through the DHT11 proprietary protocol. The serial data bits come in too fast to be treated by Python code. To include such a module we add a _user_module_ (could be any name) directory in which we create the module directory (dht11Raw in case of the DHT11). Into this directory we put the C code and a <i>micropython.mk </i>file.

In order to make the user module known and enabled by !MicroPython we must compile the interpreter with the following command (valid for the dht11Raw module):

make USER_C_MODULES=../../../user_modules -CFLAGS_EXTRA=-DMODULE_DHT11RAW_ENABLED=1

For more details about C user modules in !MicroPython see https://docs.micropython.org/en/latest/develop/cmodules.html

The source code for the example module described in the docs and the dht11Raw module can be found in this gzipped tar archive:

%ATTACHURL%/user_modules.tar.gz

-- %USERSIG{UliRaich - 2020-04-29}%

---++ Comments

%COMMENT%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
png	compileError.png	r1	manage	59.7 K	2020-04-29 - 18:02	UliRaich
png	modules.png	r1	manage	34.3 K	2020-04-29 - 18:58	UliRaich
gz	user_modules.tar.gz	r1	manage	2.2 K	2020-05-02 - 08:31	UliRaich
png	virtualEnv.png	r1	manage	161.3 K	2020-04-29 - 18:18	UliRaich

Topic revision: r3 - 2020-05-02 - UliRaich