working with Micropython - which ecosystem to choose - ESP 8266 or ESP 32?

[apollo]

dear community



working with Micropython - which ecosystem to choose - ESP 8266 or ESP 32?


I work with Kids. I'm always looking for economical platforms to build intriguing projects.

there are systematical decisions: in earlier times i use Arduino and Raspberry Pi for the projects because the eco-sytems of Arduino and Raspi support rich options to combine.

While Arduino clones are cheap, it uses the C/C++ language. that kids are not familiar with. and - yes it doesn't have a built-in WiFi-support. But that is pretty important for me.

WiFi-Support is a must for all the IoT projects i am interested in. On the other hand, while Raspberry Pi has WIFI and kids can program it using Python, it is still an pretty expensive platform to just control few GPIO ports to


1. turn devices on and off.
2. run a little RC-Car
3. have a look in the birds house that is in the garden


I need something in between that has both WIFI and Python capabilities. It appears that I found my answer in MicroPython flashed
onto a cheap ESP8266-based board - and yes - now we also can use ESP32 too.


What is Micropython?
According to its website, MicroPython is a lean and efficient implementation of the Python 3 programming languages.
And Python is one of the most widespread and well known language - also my kids have access to a lean python introduction.
In other words: Python is much easiser to learn than C /C++ - Python does not have all those pitfalls.

Micropython
that includes a small subset of the Python standard library and the good thing; Micropython is optimized to run on
microcontrollers and in constrained environment (such as ESP8266).
It's essentially Python IDE on a chip. One major benefit is that you can create code and change it on the fly using
a web-browser client called Webrepl. (Try to do that in Arduino.) You can also see sensor data in real-time on
Webrepl instead of rely on data logging or an LED screen in Arduino.


What is ESP8266?
In short, think of it as an Arduino with built-in network capability. You can use the Arduino IDE to program ESP8266 boards in C/C++ or
you can flash it with NodeMCU or MicroPython. In this project, I'll be flashing MicroPython onto an ESP8266 board.
I decided to get a WEMOS D1 which is based on ESP8266-12EX for this simple project where I'll be navigating a 2WD car using a web browser.
There are other boards that are designed for MicroPython but I wanted something cheap that I could throw away
if it didn't meet my criteria. As expected, it met all my requirements and most likely I'll be incorporating WeMos and Micropython into
future projects.

among them are ...
a. creating rc-cars
b. other IoT projects


which ESP would you decide ?

- NodeMcu Lua WIFI Internet Development Board based on ESP-12E CP2102
- Adafruit Assembled Feather HUZZAH w ESP8266 WiFi With Stacking Headers
- ESP8266 ESP-13 Web Sever WIFI Wireless Shield for Arduino UNO R3


which one would you take?

or would you choose the ESP 32 !?


love to hear from you

[apollo]

by the way: found a Micropython Library for Hobby Servo Control for ESP8266

cf: https://bitbucket.org/thesheep/micropyth...c/default/

This is a simple class for controlling hobby servos with Micropython on the ESP8266 boards.
It's in fact a simple convenience wrapper over the machine.PWM functionality.
Currently, the supported pins are 0, 2, 4, 5, 12, 13, 14, 15

-- because only those pins are supported by machine.PWM. Pins 1 and 3 may become supported in the future.

usage:
To use this library, we simply need to copy it to the ESP8266's filesystem,
or include it in the scripts directory while compiling the Micropython firmware.
cf: https://bitbucket.org/thesheep/micropyth...c/default/

work and use case:
The way the servos work is that we send them a square wave signal with a fixed frequency (for analog servos this is usually 50Hz, but the digital servos may be furthermore able to accept up to 300Hz signals):
with that the duty cycle controls the servo position exactly. The tradition is that at duty cycle of 1500µs the servo goes to its center position.

well - I have a question an an idea.
is 3V3 enough to run this!? The thing that looks interesting to me in this class is the fact,
that in the example for the ESP min is said to be 40 and max to be 115...
and I allways thought how can we make 180° out off that (Chapter 7.2)
http://docs.micropython.org/en/latest/es...obby-servo
cf: https://bitbucket.org/thesheep/micropyth...c/default/

generally spoken - and compared to the Arduino:
Then I looked into the source and saw that this used totally differnent values for min and max microseconds 600 and 2400. Afterwards i have also checked the Arduino reference and they to also took totally different values 1000 to 2000. See: Is it a depending on the servo manufacture that some values are min is 400 µs lower and the max is 400 µs larger.

the question to me: Why are the examples from the mircopython docu totaly different?
Finally i want to add an idea. What about an read method, at least the arduino has got one. ;)
https://www.arduino.cc/en/Reference/Serv...croseconds

BTW one question: - do we need that library - cannot we just start without that... - cf this post:

https://icircuit.net/micropython-control...demcu/2385
Servos are exciting devices. We can get precise posting with minimal code,
all we need is a controller that can produce PWM at 50Hz.
In this post we will understand how to use ESP32 to control Servo.
We will be using micropython to program ESP32/NodeMCU. The grate thing about MicroPython is that it is platform independent (mostly), which means code written for NodeMCU (ESP8266) can be used on ESP32 as well.

To use MicroPython on ESP32, First we need to load MicroPython Interpreter. Check out ESP32 – Getting started with MicroPython post to load interpreter and tools you can use with micro python. https://icircuit.net/esp32-micropython-g...arted/1999
If you are using NodeMCU, then refer to this post https://icircuit.net/nodemcu-getting-sta...ython/2406
MicroPython has PWM support. You can find full documentation of PWM library here http://docs.micropython.org/en/latest/es...l/pwm.html

Environment requirements:

we need a ESP32 or NodeMCU Machine with uPyCraft to load python files to the device

Controlling Servo: Connect servo signal pin to GPIO2 of the ESP, you need to power the servo as well
Code: All you need is couple of python lines to control the servo, how easy is that

import machine
p4 = machine.Pin(4)
servo = machine.PWM(p4,freq=50)
# duty for servo is between 40 - 115
servo.duty(100)

The PWM method of machine takes two inputs, the pin to which we want connect servo
(in case of ESP8266 we can choose one from 0, 2, 4, 5, 12, 13, 14 and 15) and frequency of the PWM signal.
Most of the hobby servos work with 50Hz PWM, so we choose that. Then we can use duty method to set the angle
we can call servo.duty() method to change the set the servo angle

love to hear from you