Tag Archives: Electronics

Bodgers – More Distance Sensors

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This week we are going to try making a measuring device using our HC-SR04 sensors.

First we’ll wire our circuit up.

Next let’s test our circuit with the following code.

from machine import Pin
import utime
from time import sleep

trigger = Pin(17, Pin.OUT)
echo = Pin(16, Pin.IN, Pin.PULL_DOWN)
buzzer = Pin(15, Pin.OUT)


def ultra():
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(5)
    trigger.low()
    while echo.value() == 0:
        signaloff = utime.ticks_us()
    while echo.value() == 1:
        signalon = utime.ticks_us()
    timepassed = signalon - signaloff
    distance = (timepassed * 0.0343) / 2
    print("The distance from object is ", distance, "cm")
    return distance


def buzz():
    buzzer.value(1)
    sleep(0.5)
    buzzer.value(0)
    sleep(0.5)


while True:
    dist = ultra()
    if dist < 30:
        buzz()
    utime.sleep(1)

This week’s challenge is to rewrite the code so the the closer to something the sensor is the faster it will beep.

Once we have that done we will look at transferring the code onto the Pico itself and running it from a battery.

Bodgers – Distance Sensors

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This week we will be using the HC-SR04 Ultrasonic Distance Sensor

Wire up the sensor as shown below

Here is the code we will need for the sensor.

#From www.tomshardware.com/how-to/raspberry-pi-pico-ultrasonic-sensor
from machine import Pin
import utime

trigger = Pin(17, Pin.OUT)
echo = Pin(16, Pin.IN, Pin.PULL_DOWN)

def ultra():
   trigger.low()
   utime.sleep_us(2)
   trigger.high()
   utime.sleep_us(5)
   trigger.low()
   while echo.value() == 0:
       signaloff = utime.ticks_us()
   while echo.value() == 1:
       signalon = utime.ticks_us()
   timepassed = signalon - signaloff
   distance = (timepassed * 0.0343) / 2
   print("The distance from object is ",distance,"cm")

while True:
   ultra()
   utime.sleep(1)

Once this is working you can move on to this week’s challenge. Combine this with the LED code from the last session so that the LED flashes when the distance measured by the sensor is less than 30CM. Here is the LED code:

from machine import Pin
from time import sleep

led = Pin(15, Pin.OUT)

def flash():
    led.value(1)
    sleep(0.5)
    led.value(0)
    sleep(0.5)
    
while True:
    flash()

Bodgers – RFM69 Radio Modules

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DSC00227

Hello again everyone.

This week we looked at the Adafruit RFM69HCW Radio Module, these modules allow us to send messages between Arduinos without using Wifi or Bluetooth.

Adafruit have a tutorial here on setting up the module. The basic steps are:

  1. Solder on the header pins.
  2. Solder antenna or wire cut to the the proper length for the module/frequency
    • as our frequency is 433 MHz  we cut the wire to 16.5 cm.
  3. Wire up modules to your Arduinos
  4. Download the RadioHead library to your Arduino IDE.
  5. Load the RadioHead69_RawDemo_TX code from this library to the Arduino you’re using to transmit.
  6. Load the RadioHead69_RawDemo_RX code from this library to the Arduino you’re using to receive.
  7. Test

Next Saturday we will be putting all of the different components from our projects together and testing out how they work.

see you all then.

Declan, Dave and Alaidh

Bodgers – Introduction to Arduino

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Hello again everyone.

I was away this week so Dave led the group, they did a couple of Arduino projects. They  revisited the traffic lights from December but this time used the Arduino to control them and then moved on to  a temperature and humidity sensor called the DHT11.

 

Here is the wiring diagram for  the traffic lights and you can find the code here.

arduino lights

 

Here is the wiring diagram for the DHT11 and the code is also on Dropbox here.

dht

We will be doing more with the Arduino particularly for some of our projects.

See you All again on Saturday

Declan, Dave and Alaidh

Bodgers – Traffic Light with Buzzer

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This week we continued working with GPIO Zero, at the end of last week’s session we had started working on a simple LED traffic light, we finished of that this week and we added a buzzer to it.

circuit2

I had hoped to work on the HC-SR04 distance sensor but there seems to be an issue with them on the Raspberry Pi at the Moment.

Here is a video that demonstrates what we covered on Saturday.

See you all next Saturday (08-Dec) for our Christmas party.

Declan, Dave and Alaidh

 

Bodgers – Making Pictures With LEDs

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Hello again everyone.

We started of this week’s session by looking at the recent Soyuz rocket launch which was to send two people to the ISS. During the launch one of the booster rockets failed and the launch had to be aborted. Both crew members, astronaut Nick Hague and cosmonaut Aleksey Ovchinin, escaped without injuries.

Official astronaut portrait of Tyler (Nick) Hague – Blue Flight Suit Picture. Photo Date: January 13, 2014. Location: Building 8, Room 183 – Photo Studio. Photographer: Robert Markowitz

We then continued to work on our pictures and messages for the Mission Zero Challenge. I made a video of some of the work we did, but it’s very hard to film LEDs so the quality is very poor.

If you want to find out more about the Soyuz incident and have another look at how to make pictures and messages with the Sense-hat LEDs my notes are here day 4.

Next Saturday we’ll start looking at Pygame Zero. See you all then.

Declan, Dave and Alaidh

Bodgers – Making With Trinket.io

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Hello again everyone.

In the Bodgers group,  we’ve been working on code for the International Space Station. To do this we are using on online Sense Hat emulator, the Sense Hat is a special piece of hardware designed to be deployed with a Raspberry Pi on the ISS.

Capture15

The online emulator is available at https://trinket.io/sense-hat and there’s a good tutorial on the Raspberr Pi website here https://projects.raspberrypi.org/en/projects/astro-pi-mission-zero.

Here is our Trinket https://trinket.io/python/04b90b70cf.

You can play around with these and we will probably finish up with the Mission Zero Challenge for while after Saturday. My slides from last Saturday are here day 3.

See you all on Saturday.

Declan, Dave and Alaidh

Bodgers – Making For The International Space Station

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Hello again everybody.
This week in the Bodgers group we started working on our code for the Mission Zero Challenge.

mission-zero-logo

We began by writing a simple text message on the 8×8 full-colour LED display, then we changed the text and background colours. We then coded a picture by assigning a colour to each of the 64 LEDs on the display. We finished the session by taking a quick look at using the temperature sensor to read the temperature. Here are my slides from this week day 2.
Next week we will recap what we covered this week and we will start to personalise our code for the challenge.

In the meantime, here’s a couple of fun videos on how the Astro Pi computers got to the ISS.

See you all next Saturday

Declan, Dave and Alaidh

Bodgers – RPM & KPH

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Last Saturday we had a look at how we might figure out how far and how fast a bike is going using a Raspberry Pi. We used a very basic set up with just a micro-switch attached to a toy trike with a little nut taped to the front wheel, each time the wheel rotates the nut would “click” the micro-switch.IMG_20180214_122408

We would need to use a reed switch or a hall effect sensor and a magnet attached to the wheel if we were to use this on a real bike.

We started of our coding by looking at the time.time() function. This function returns the number of seconds, in decimal form, since 01 January 1970. If we want to time an event all we have to do is use time.time() to get the start time and use it again to get the end time and then subtract the the start time from the end time.

We used this to get the the amount time it takes to do one rotation. Now we want to find out how many rotations we have per minute or RPM (revolutions per minute). As our result is in seconds the easiest thing to do is calculate revs per second so we divide 1 by the time it takes to do 1 rotation and then multiply the answer by 60 to get RPM.

Now we wanted to get KPH(kilometres per hour) so first we measured the circumference of the wheel and found it was 50cm or 0.5 Metres. We then calculated metres per minute by multiplying our RPM by 0.5 and we then multiplied this by 1000 to get KPH.

Here’s a picture of what our results could look like when displayed using Pygame. We will look at Pygame later on as it’s an excellent way of displaying information.IMG_20180214_122722

See you all after the break.

Declan, Dave and Alaidh

Bodgers – New Kit & New Projects

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Hello again Everyone.

Last week in the Bodgers group we began by looking at our new keyboards and Touchscreens. These will allow us to easily design touch based projects and projects that need a monitor. They will also be invaluable at the start of next years sessions as we can get our code on the Raspberry Pi straight away without any need to connect our laptops.

IMG_20180203_140614

We also started planning our next project with a short brainstorming session and we have a couple of ideas we will develop further this week.

 

See you on Saturday.

Declan, Dave and Alaidh