NodeMCU Projects

Micropython

Basics

• Installing:

sudo pip install esptool
esptool.py --port /dev/ttyUSB0 erase_flash
esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 ~/Desktop/esp8266-20171101-v1.9.3.bin

• Connecting via Terminal:

sudo apt install picocom
picocom /dev/ttyUSB0 -b115200

• Connecting via REPL(web):

import webrepl_setup

If you disabled automatic start-up on boot, you may run configured daemon on demand using:

import webrepl
webrepl.start()

• Checking filesystem:

import os
os.listdir()

• Create directories:

os.mkdir('dir')

• Remove Files:

os.remove('data.txt')

• Writing Data to files:

f = open('data.txt', 'w')
f.write('some data')
f.close()

• Reading data:

f = open('data.txt')
f.read()
f.close()

• Checking Machine Frequency & Overclocking:

import machine
machine.freq()                # get the current frequency of the CPU
machine.freq(160000000)       # set the CPU frequency to 160 MHz

• Check AP Name:

import network;
ap = network.WLAN(network.AP_IF);
print(ap.config('essid'));

• Change AP name and password:

import network;
ap = network.WLAN(network.AP_IF);
ap.active(True);
ap.config(essid='MyESP8266', authmode=network.AUTH_WPA_WPA2_PSK, password='mypassword');
print(ap.config('essid'));

• Boot Process:

As a final step of boot procedure, main.py is executed from filesystem
This file is a hook to start up a user application each time on boot (instead of going to REPL). 
For small test applications, you may name them directly as main.py
but instead it’s recommended to keep your application(s) in separate files, and have just the following in main.py:

import my_app
my_app.main()

• Upload data using Serial Port

sudo pip install adafruit-ampy
ampy --port /dev/ttyUSB0 put ~/Desktop/main.py

Projects

Playing with GPIO

import machine
import time
import urandom

pin = machine.Pin(2, machine.Pin.OUT)

def toggle(p):
   p.value(not p.value())

while True:
   time.sleep_ms(urandom.getrandbits(8))
   toggle(pin)

Fading an LED

import time, math
import machine

led = machine.PWM(machine.Pin(2), freq=1000)

def pulse(l, t):
    for i in range(20):
        l.duty(int(math.sin(i / 10 * math.pi) * 500 + 500))
        time.sleep_ms(t)

while True:
    pulse(led, 20)

Control a hobby servo

Hobby servo motors can be controlled using PWM. 
They require a frequency of 50Hz and a duty between about 40 and 115, with 77 being the center value. 

• Manual Movements

servo = machine.PWM(machine.Pin(12), freq=50)
servo.duty(40)
servo.duty(115)
servo.duty(77)

• Random movements:

servo = machine.PWM(machine.Pin(12), freq=50)
while True:
   servo.duty(urandom.getrandbits(8))
   time.sleep(1)

• Analog Temperature Meter:

Requirements:

DS18B20 Temperature sensor
Servo Motor
Micropython based NodeMCU

Wiring details:

Servo motor = D4 => GPIO 2
DS18B20     = D7 => GPIO 13

import time
import machine
import onewire, ds18x20

# the device is on GPIO13
dat = machine.Pin(13)

# create the onewire object
ds = ds18x20.DS18X20(onewire.OneWire(dat))

# scan for devices on the bus
roms = ds.scan()
print('found devices:', roms)

# servo is connected to GPIO2
servo = machine.PWM(machine.Pin(2), freq=50)

# Function for mapping range
def translate(value, leftMin, leftMax, rightMin, rightMax):
    # Figure out how 'wide' each range is
    leftSpan = leftMax - leftMin
    rightSpan = rightMax - rightMin

    # Convert the left range into a 0-1 range (float)
    valueScaled = float(value - leftMin) / float(leftSpan)

    # Convert the 0-1 range into a value in the right range.
    return rightMin + (valueScaled * rightSpan)
 
# print all temperatures
while True:
    ds.convert_temp()
    time.sleep_ms(1000)
    for rom in roms:
        print(ds.read_temp(rom))
    temp = ds.read_temp(rom)
    srv = translate(temp, 20, 35, 40, 115)
    print(int(srv))
    if (temp>=20) & (temp<=35):
        servo.duty(int(srv))
    else:
        print("Out of Range")

References

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