RC Car with esp8266 and MicroPython - an approach with code

[say_hello]

 

dear community

 

At the beginning of my story I have to say, that this was my first time to IOT topic - and to the ESP32 and 8266  

I'm a complete beginner, but one thing I have is the desire to known new technologies.

 

A month ago my colleague make presentation about #esp8266 and I was impressed this small board. So I decided that I would like to known more about #esp8266 and similar stuff.

I use Micropython (http://micropython.org/download) it is a firmware for the #esp8266 boards. At the beginning i have to underestand how it works, but I have read allmost a ton of webpages and articles about it.

 

some ideas regarding the aims:

 

What is needed for the car: We need to meet some conditions with the RC-car.

 

We ......:

 

- have the car expect one command every second. If it does not receive one, it stops.
- We can of course use the connection type that fits our existing hardware or use-case best. Once we have decided that, the search for a good connection library starts.

well - if i want to go with some web-app or pc controlled thing, then i should choose TCP/IP / WIFI or bluetooth ( with ESP 32)

regarding the hardware:

 

firstly: I would say that i should not make use of an Uno and an esp-01 module. This makes life much more difficult.
i think that i should choose a Wemos Mini D1 or a nodeMCU board.  This will be smaller, cheaper and easier to use.

secondly perhaps i should choose a less old-fashioned motor driver than the 298. These will work well with 3.3V circuits,
be more efficient and maybe use fewer pins (which may be important when using the Wemos/nodeMCU). What do you think  about this idea.

thirdly i think that i have to go with MicroPython: - it is a pretty intersting approach to stick - working with ESP8266 or ESP32

btw regarding the use of MicroPython i have found an interesting approach here:

written by david golak:
https://hackaday.io/project/27444-remote-control-car-via-wifi
How to build RC Car with the esp8266.

see the code https://github.com/dgolak/esp8266/blob/master/main.py

 

 

import machine
import time
LED_PIN=15
led=machine.Pin(LED_PIN,machine.Pin.OUT)
led.off()
LIGHT_PIN_L=13
light_l=machine.Pin(LIGHT_PIN_L,machine.Pin.OUT)
light_l.off()
LIGHT_PIN_R=2
light_r=machine.Pin(LIGHT_PIN_R,machine.Pin.OUT)
light_r.off()
class engines:
    def __init__(self, machine):
        self.machine = machine
        self.left_first_pin = 0
        self.left_second_pin = 5
        self.right_first_pin = 14
        self.right_second_pin = 12
    def forward(self, duty=1000):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_first_pin),freq=100,duty=duty)
        e2=machine.PWM(self.machine.Pin(self.right_first_pin),freq=100,duty=duty)
    def backward(self, duty=1000):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_second_pin),freq=100,duty=duty)
        e2=machine.PWM(self.machine.Pin(self.right_second_pin),freq=100,duty=duty)
    def left_up(self):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_first_pin), freq=100, duty=400)
        e2=machine.PWM(machine.Pin(self.right_first_pin), freq=100, duty=1000)
    def right_up(self):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_first_pin),freq=100,duty=1000)
        e2=machine.PWM(self.machine.Pin(self.right_first_pin),freq=100,duty=400)
    def left_down(self):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_second_pin), freq=100, duty=400)
        e2=machine.PWM(machine.Pin(self.right_second_pin), freq=100, duty=1000)
    def right_down(self):
        self.stop()
        e1=machine.PWM(self.machine.Pin(self.left_second_pin),freq=100,duty=1000)
        e2=machine.PWM(self.machine.Pin(self.right_second_pin),freq=100,duty=400)
    def stop(self):
        machine.PWM(self.machine.Pin(self.left_first_pin),freq=0,duty=0)
        machine.PWM(self.machine.Pin(self.right_second_pin),freq=0,duty=0)
        machine.PWM(self.machine.Pin(self.left_second_pin),freq=0,duty=0)
        machine.PWM(self.machine.Pin(self.right_first_pin),freq=0,duty=0)
E=engines(machine)
try:
    import usocket as socket
except:
    import socket
CONTENT = b"""\
HTTP/1.0 200 OK
Hello #%d
"""
CONTENT = b"""\
HTTP/1.0 200 OK
Content-Type: text/html\n\r
<html>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js" type="text/javascript" charset="utf-8">
  </script>
<head>
<script type="text/javascript">
var DEVICE_URL = 'http://%s'
function iotAction(action){
    if(action=='change_led'){
        if(document.getElementById('led_value').value==1){
            action='led_off'
            document.getElementById('led_value').value=0
            document.getElementById('led_control').style.backgroundImage="url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/alarm_off.jpg')"
        }else if(document.getElementById('led_value').value==0){
            action='led_on'
            document.getElementById('led_value').value=1
            document.getElementById('led_control').style.backgroundImage="url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/alarm_on.jpg')"
        }else{
            action="led_on"
        }
    }
    if(action=='change_light'){
        if(document.getElementById('light_value').value==1){
            action='light_off'
            document.getElementById('light_value').value=0
            document.getElementById('light_control').style.backgroundImage="url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/light_off.jpg')"
        }else if(document.getElementById('light_value').value==0){
            action='light_on'
            document.getElementById('light_value').value=1
            document.getElementById('light_control').style.backgroundImage="url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/light_on.jpg')"
        }else{
            action="light_on"
        }
    }
    var requestURL = DEVICE_URL + "/?action="+action
    $.get (requestURL)
}
</script>
<style>
#container{
    width:800px;
    height:1300px;
    background-image:url("https://raw.githubusercontent.com/dgolak/esp8266/master/images/navi2.png");
    background-position:40px 110px;
    background-size:720px;
    background-repeat: no-repeat;
    -webkit-user-select: none;
    padding-top:100px;
}
button{
    background-color:transparent;
    border-color:transparent;
    border:0px solid red
}
</style>
</head>
<center>
<div id="container">
<table cellpadding="0" cellspacing="0">
<tr>
<td style="padding-left:130px;" colspan="3">
<button style="width:440px;height:150px" ontouchstart="iotAction('forward')" ontouchend="iotAction('stop')"/>
</td>
</tr>
<tr>
<td><button style="width:180px;height:190px" ontouchstart="iotAction('left_up')" ontouchend="iotAction('stop')"/></td>
<td rowspan="2"><button style="width:350px;height:370px" ontouchstart="iotAction('stop')" ontouchend="iotAction('stop')"/></td>
<td><button style="width:180px;height:190px" ontouchstart="iotAction('right_up')" ontouchend="iotAction('stop')"/></td>
</tr>
<tr>
<td><button style="width:180px;height:220px" ontouchstart="iotAction('left_down')" ontouchend="iotAction('stop')"/></td>
<td><button style="width:180px;height:220px" ontouchstart="iotAction('right_down')" ontouchend="iotAction('stop')"/></td>
</tr>
<tr>
<td style="padding-left:130px;" colspan="3">
<button style="width:440px;height:150px" ontouchstart="iotAction('backward')" ontouchend="iotAction('stop')"/>
</td>
</tr>
</table>
<br/><br/>
<table>
<tr>
<td>
<input type="hidden" id="light_value" value="0"/>
<button id="light_control" style="width:200px;height:200px;background-image:url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/light_off.jpg');background-size:200pxontouchstart="iotAction('change_light')"></button>
</td>
<td>
<input type="hidden" id="led_value" value="0"/>
<button id="led_control" style="margin-left:20px;width:200px;height:200px;background-image:url('https://raw.githubusercontent.com/dgolak/esp8266/master/images/%s');background-size:200pxontouchstart="iotAction('change_led')"></button>
</td>
</tr>
</table>
</div>
</center>
</html>
"""

def main(E,micropython_optimize=False):
    s = socket.socket()
    ai = socket.getaddrinfo("172.20.10.10", 80)
    addr = ai[0][-1]
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    s.bind(addr)
    s.listen(5)
    while True:
        res = s.accept()
        client_sock=res[0]
        if not micropython_optimize:
            client_stream = client_sock.makefile("rwb")
        else:
            client_stream = client_sock
        req = client_stream.readline()
        get = req.split()[1].decode('utf-8')
        if get == '/?action=forward':
            E.forward()
        elif get == '/?action=left_up':
            E.left_up()
        elif get == '/?action=right_up':
            E.right_up()
        elif get == '/?action=left_down':
            E.left_down()
        elif get == '/?action=right_down':
            E.right_down()
        elif get == '/?action=backward':
            E.backward()
        elif get == '/?action=stop':
            E.stop()
        elif get == '/?action=led_on':
            led.on()
        elif get == '/?action=led_off':
            led.off()
        elif get == '/?action=light_on':
            light_l.on()
            light_r.on()
        elif get == '/?action=light_off':
            light_l.off()
            light_r.off()
        else:
            pass
        while True:
            h = client_stream.readline()
            if h == b"" or h == b"\r\n":
                break
        if led.value() == 1:
            led_icon="alarm_on.jpg"
        else:
            led_icon = "alarm_off.jpg"
        client_stream.write(CONTENT % (wlan.ifconfig()[0],led_icon))
        client_stream.close()
        if not micropython_optimize:
            client_sock.close()
main(E)

see  https://github.com/dgolak/esp8266/blob/master/main.py

well i guess that this is a straingthforward approach...

cf:  david golak:
https://hackaday.io/project/27444-remote-control-car-via-wifi
How to build RC Car with the esp8266.

btw: my car has got a option of a steering axle - in other words - i have a slightly different car  - than David has.
But that i think does not make a big difference.. I have to change the code at some places to fit.

i will have a closer look at this.

 

regards

 

[carmatic]

in my opinion, as far as the RC car system goes, you should just get an off the shelf toy RC car, then remove the original radio system, but leave the steering servo and onboard motor controller intact... this way it is probably cheaper, and saves you the headache of building the mechanics like the drivetrain, the battery compartment, where all the components are mounted, etc etc, and you have an already working steering axle system
there is a possibility that the motor controller is intergrated into the receiver circuitry in the case of the nastily cheap toys, in that case you will have to buy separate speed controller from a hobby shop, it shouldn't cost too much money

then, you interface the esp8266 with the servo and the motor controller using this https://www.instructables.com/id/Interfacing-Servo-Motor-With-NodeMCU/ ... the motor controller uses the same signals as the servo, you connect the servo to one of the outputs and the motor controller to a different output, and change the code accordingly

 

 

 

Edited February 3, 2019 by carmatic

[carmatic]

i see in the code that there is a reference to PWM signals being output from pin 13 and pin 2, if you want to control a steering servo and a motor speed controller (they use the same signals), read this https://learn.sparkfun.com/tutorials/hobby-servo-tutorial