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• Type: Drillpro Woodworking Cutter
• Material: HSS
• Shank Diameter: 3.175mm
• Length: about 40mm
• Box Size: 87x52x10mm (L*W*H)

The Raspberry Pi is a great computer but there's just one thing that most hardware hackers will find missing: a few inputs for connecting analog sensors. This is where the MCP3008 chip comes in handy, with eight 10-bit channels accessible over SPI. Thanks to the Raspberry Pi's SPI interfaces and its two 'Chip Select' pins available off of the main GPIO connector, the problem is solved.

Features

• 10-bit resolution
• ± 1 LSB max DNL
• ± 1 LSB max INL
• 8 input channels
• Analog inputs programmable as single-ended or pseudo-differential pairs
• On-chip sample and hold
• SPI serial interface (modes 0,0 and 1,1)
• Single supply operation: 2.7V - 5.5V
• 200 ksps max. sampling rate at VDD=5V
• 75 ksps max. sampling rate at VDD=2.7V
• Low power CMOS technology
• 5 nA typical standby current, 2 µA max.
• 500 µA max. active current at 5V
• Industrial temp range: -40°C to 85°C

Applications

• Sensor Interface
• Process Control
• Data Acquisition
• Battery Operated Systems

How-To

The following sample assumes that you're running the latest official Raspbian distribution, that you're logged in as root and that you haven't yet customized Raspbian to use SPI from a Python script. By default, the kernel module managing SPI communications is not loaded on Raspbian, so let's ensure that the 'spidev' device is available.

[email protected]:/# lsmodModule                  Size  Used by  snd_bcm2835            12808  0  snd_pcm                74834  1 snd_bcm2835  snd_seq                52536  0  snd_timer              19698  2 snd_seq,snd_pcm  snd_seq_device          6300  1 snd_seq  snd                    52489  5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835  snd_page_alloc          4951  1 snd_pcm  

If 'spidev' device is not listed, we need to remove it from the kernel module 'blacklist' so that it's automatically loaded on the next boot:

[email protected]:/# nano /etc/modprobe.d/raspi-blacklist.conf  

Put a hash character in front of the 'blacklist spi-bcm2708' statement and save the file:

#blacklist spi-bcm2708  

then, manually load the SPI device:

[email protected]:/# modprobe spidev  

The command should just complete without returning an error. Validate the list of modules:

roo[email protected]:/# lsmod  Module                  Size  Used by  spi_bcm2708             4401  0  spidev                  5136  0  snd_bcm2835            12808  0  snd_pcm                74834  1 snd_bcm2835  snd_seq                52536  0  snd_timer              19698  2 snd_seq,snd_pcm  snd_seq_device          6300  1 snd_seq  snd                    52489  5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835  snd_page_alloc          4951  1 snd_pcm  

The 'spidev' device should now be available.

Next, install the 'git' package. It will be needed to install other packages from Github.

apt-get install git-core  

Install the 'python-dev' package. It will be needed to compile the 'py-spidev' package.

apt-get install python-dev  

Download and compile the 'py-spidev' package.

[email protected]:/# cd /home  [email protected]:/home# git clone git://github.com/doceme/py-spidev  [email protected]:/home# cd py-spidev/  [email protected]:/home# python setup.py install  

At this point, SPI is available from Python 2.7. Assuming that you have wired the MCP3008 to the Raspberry Pi's SPI bus using CE0 as the 'chip select' pin, you can read all eight analog inputs using the following Python script.

[email protected]:/home# nano adc.py  

Paste the script below in the editor and save it.

import spidev  import time    spi = spidev.SpiDev()  spi.open(0,0)    # read SPI data from MCP3008 chip, 8 possible adc's (0 thru 7)  def readadc(adcnum):          if ((adcnum > 7) or (adcnum < 0)):                  return -1          r = spi.xfer2([1,(8 adcnum)<<4,0])          adcout = ((r[1]&3) << 8)   r[2]          return adcoutwhile True:          for adcInput in range(0,8):                  print "ADC(", adcInput,")=", readadc(adcInput)          time.sleep(1)  

To execute the script

[email protected]:/home# python adc.py  

Sample output using a 10K Ohm trimpot connected to the ADC's pin 3 and all other pins pulled down to ground using a 10k resistor.

ADC( 0 )= 0  ADC( 1 )= 0  ADC( 2 )= 0  ADC( 3 )= 507  ADC( 4 )= 0  ADC( 5 )= 0  ADC( 6 )= 0  ADC( 7 )= 0  

Credits go to Jeremy for his work on the 'py-spidev' Python module which makes working with the MCP3008 straight forward. Alternatively, checkout wiringPi's SPI functions if you prefer using a 'C' API.

Related Tutorials & Samples

• Loading I2C, SPI and 1-Wire drivers on the Raspberry Pi
• Jeremy's Blog: Raspberry Pi hardware SPI analog inputs using the MCP3008
• wiringPi 'C' API for interfacing with SPI, I2C, GPIOs and more
• Adafruit Learning System
  • Save and Graph Analog Temperature Data
  • Converting analog inputs to digital and control audio volume

Description:

The MonkMakes Relay for micro:bit is a solid-state (no moving parts) relay that allows an output of a micro:bit to turn things on and off.

A micro:bit can turn an LED on and off directly, but anything more powerful requires something like a relay or a transistor. Using a transistor to switch something on and off requires a shared ground connection with the micro:bit and a knowledge electronics that you or your students may not be ready for. The MonkMakes Relay for micro:bit is much easier to use, acting like a simple micro:bit controlled switch.

This relay can be used to switch low voltage devices such as light bulbs, a motor, a small heating element or even a string of 12V LED lighting. The voltage needs to be kept under 16V, but the relay will automatically protect itself against too much current.

FEATURES

• Solid-sate relay (up to 2 Amps)
• Active LED indicator
• Resettable ‘polyfuse’ to protect against over-current

Getting Started

Connecting your micro:bit

The Relay requires just two connections to the micro:bit. One to GND (ground) and one to whatever pin is to be used to control the relay’s switching action.

When attaching the alligator clips to the micro:bit, make sure that the clips are perpendicular to the board so that they are not touching any of the neighbouring connectors on the micro:Bit edge connector.

Here’s an example of how you could wire up a MonkMakes Relay for micro:bit to turn an old fashioned light bulb on and off.

HEX File

The quickest way to try out your relay is to DOWNLOAD THIS HEX FILE >and then copy it onto your micro:bit. The program will turn the relay on and off once a second.

JavaScript Blocks Editor

Set the controlling pin to 1 and the relay contacts will close, set it to 0 and the contacts will open again. Its as simple as that. So, to make your relay turn on and off once a second, open the Blocks Editor, add a forever block and then the digital write blocks from the pins category and the pauses from the basic category.

MicroPython

Paste the following code into the Python window and then Download the file and copy it onto your your micro:bit.

from microbit import *

while True:
    pin0.write_digital(True)
    sleep(500)
    pin0.write_digital(False)
    sleep(500)

Analog Outputs

The latest MonkMakes Relay for micro:bit can do more than just switch things on and off. It can also be used with micro:bit analog outputs. Look closely at your Relay for micro:bit and is it has the version number v1ev (under the word ‘Board’) then it can be used with the ‘analog write’ block in the blocks editor or the ‘write_analog’ function in MicroPython. If your board has the version number v1e then it is not suitable for use with analog outputs – sorry you were unlucky to get one of the small batch of first boards to be sold.

The output of the Relay for micro:bit is not linear at low PWM and high PWM values as the following chart illustrates.

The y-axis shows the current in mA for a test load resistor supplied from a constant voltage source. The x-axis is the analog write value (0 to 1023). As you can see, there is a dead zone up to a analog output value of about 100, followed by a relatively good linear region right up to about 1000, after which the output effectively becomes ‘on’.

The tests were carried out at the default PWM frequency of 50Hz for the micro:bit. Lower frequency PWM is expected to produce more linear results.

Description:

The MonkMakes Sensor Board for micro:bit allows you to sense sound level, temperature and light level.

Features

• 3V and GND connections can be made from either side and allow you to power a second board such as the MonkMakes Relay Board or MonkMakes Speaker.
• LED ‘power on’ indicator
• Reverse polarity protection
• All three sensors are analog and can be connected to pins P0, P1 and P2 using alligator clips.

Getting Started

Connecting to your micro:bit

You only have to wire up the sensors that you are actually using, but you could wire all the sensors up as shown below. The code examples below assume that pin 0 is used for sound, pin 1 for temperature and pin 2 for light. You can use any pin for any of the sensors, but remember to modify the code to match the pin you are using.

Sound

The Sensor for micro:bit uses a MEMs (microphone on a chip) and a pre-amplifier. The output of the sound sensor is connected to an analog input where it can be sampled. The sound signal varies about the 1.5V level. So, silence will produce an analog output of around 1.5V. When there is sound the analog readings will oscillate above and below the 1.5V level like this:

This is why 511 is subtracted from the readings in the code examples below.

JavaScript Blocks Editor

Here is an example of using the Sensor Board to display a bargraph to indicate the sound level. Click on the image below to try it out. Making a noise into the microphone will make the LEDs dance.

MicroPython

from microbit import *

def bargraph(a):
display.clear()
for y in range(0, 5):
if a > y:
for x in range(0, 5):
display.set_pixel(x, 4-y, 9)

while True:
sound_level = (pin0.read_analog() - 511) / 100
bargraph(sound_level)

Temperature

The Sensor for micro:bit uses a thermistor to measure temperature. The temperature output from the board is a voltage that indicates the temperature. This is then measured using an analog input on the micro:bit.

The calculations for converting this voltage reading to an actual temperature are quite complicated and so the code examples here will only give a rough idea of temperature.

If you want your temperatures in Fahrenheit, then multiply the temperature in degrees C by 9, divide the result by 5 and then add 32.

JAVASCRIPT BLOCKS EDITOR

This is an example of using the Sensor Board to display the temperature, try putting your finger on the temperature sensor to warm it up. You can run the example below by clicking on it.

MicroPython

from microbit import *

while True:
reading = pin1.read_analog()
temp_c = int(reading / 13.33 - 14)
display.scroll(str(temp_c))
sleep(500)

Light

The light sensor uses a phototransistor to measure the light level and produces an output voltage that increases as the light level increases. Here is a guide to the kind of light level you might get from the sensor under different conditions (0 to 1023).

• Dark 0 to 3
• Dimly lit room 6 to 10
• Indoors directly under a light 10 to 50
• Outdoors (dull day) 100 to 200
• Outdoors (sunny day) 800 to 900

Even though the maximum analog read value is 1023, the maximum reading from this sensor is around 900.

JAVASCRIPT BLOCKS EDITOR

Here is an example of using the Sensor Board to display a bargraph to indicate the light level. Click on the image below to try it out. Put your finger over the light sensor to make it dark or shine a flash-light onto it to make more LEDs light up.

MicroPython

from microbit import *

def bargraph(a):
display.clear()
for y in range(0, 5):
if a > y:
for x in range(0, 5):
display.set_pixel(x, 4-y, 9)

while True:
light_level = pin2.read_analog() / 10
bargraph(light_level)

Description:

This motor driver board for the micro:bit allows two motors to be driven with forward, reverse, and stop control, and allows access to the other pins.

This board provides a simple way to add motor driving capability to a micro:bit. It allows two motors to be driven with full forward, reverse & stop control. It has terminal blocks to connect four input devices and a regulated 3V supply is fed in to the 80 way connector to power the inserted micro:bit.

In this new version, the pins from the micro:bit are now broken out to pads on the end of the motor driver board. These pads can either be soldered onto directly, or they are the correct spacing for our PCB pin headers (see image below for a close up of the new pads).

It is ideal for designs such as buggies (see below).

It includes an integrated edge connector slot for your micro:bit to easily slot into. It also features external connections to the buttons A and B inputs. This allows additional switches to be connected to the motor driver board and the state of these can then be read by the micro:bit.

Get up to speed quickly. Example Microsoft TouchDevelop code and example connections in the datasheet (below).

Features:

• Drive 2 motors with full forward, reverse, and stop control
• Terminal blocks for easy connection of motors and inputs
• 4 inputs (2 analogue inputs and 2 provide external connections to buttons A and B as inputs)
• Includes edge connector for the micro:bit to slot into
• Provide regulated power to the micro:bit
• Access the other micro:bit pins easily and conveniently

Contents:

• 1 x edge connector motor driver board for the micro:bit

Dimensions:

• Length: 67mm
• Width: 61mm
• Height: 18mm

Resources:

• Kitronik Custom Motor Driver MakeCode Editor Blocks (Use this URL to add them to the MakeCode Editor).
• Datasheet.

The MonkMakes Speaker for micro:bit is a neat little amplified speaker that connects to your micro:bit using alligator clips.

Features

• Amplified output
• LED ‘power on’ indicator
• Reverse polarity protection

Getting Started

Connecting to your micro:bit

Connect the Speaker to the micro:bit as shown below. When attaching the alligator clips to the micro:bit, make sure that the clips are perpendicular to the board so that they are not touching any of the neighbouring connectors on the micro:Bit edge connector.

HEX File

The quickest way to try out your speaker is to DOWNLOAD THIS HEX FILE and then copy it onto your micro:bit. Press Button A to hear a tune being played.

JavaScript Blocks Editor

Visit the Blocks Editor in your browser and then from the input section add an on button A pressed block then from the music section add a start melody block and select the tune you want to play (in this case, entertainer).

Click Download and then copy the file onto your micro:bit.

You can also make a simple musical instrument, using this tutorial: https://makecode.microbit.org/projects/hack-your-headphones/code

MicroPython

Paste the following code into the Python window and then Download the file and copy it onto your your micro:bit

from microbit import *
import music

while True:
    if button_a.was_pressed():
        music.play(music.ENTERTAINER)

When you press button A you will hear the tune “The Entertainer” play through the speaker.

Watch the video: https://youtu.be/mu4klw-N8sw

This pre-built Edge Connector Breakout Board for the micro:bit gives access to all the important pins on the bottom edge of the micro:bit.

Looking to do more with your micro:bit? Unlock its potential with this pre-built version of our Edge Connector Breakout Board! This breakout board has been designed to offer an easy way to connect additional circuits and hardware to the pins on the edge of the micro:bit. It provides access to all of the micro:bit processor pins allowing a lot of extra functionality to be added. The datasheet (below) includes a helpful diagram explaining the function of every pin on the micro:bit.

This Edge Connector Breakout Board for the micro:bit gives access to all of the important pins on the bottom edge of the micro:bit. 21 pins are broken out in total; providing additional I/O lines, direct access to buttons A and B, the LED matrix outputs and the I2C bus. Please refer to the datasheet below for more details.

The micro:bit pins are broken out to a row of pin headers. These provide an easy way of connecting circuits using jumper wires. The SCL and SDA pins are separated at the edge of the board (solder pads) providing easy identification. The PCB includes a prototyping area with 3V, 0V and unconnected rows that can be soldered to. This allows the easy connection of switches, sensors and any pull-up or pull-down resistors etc. as required.

To use the breakout board the micro:bit should be inserted firmly into the connector as shown below:

Note:

• This product is supplied with straight double row PCB pin headers already soldered to the breakout board

Features:

• Features a dedicated pin strip for quick and easy prototyping
• Breaks out 21 pins from the edge of the micro:bit
• Dedicated prototyping area with 3V and 0V rows
• Labelled pins and clear, straightforward documentation

Contents:

• 1 x Edge Connector Breakout Board for the micro:bit, pre-built

Dimensions:

• Length: 60mm
• Width: 40mm
• Height: 11.8mm

Requires:

• 1 x micro:bit

Resources:

• Click here to download the datasheet.

pin:bit breaks out all of the useful pins from your micro:bit into breadboard format while providing handy-dandy labels to make your builds go smoothly.

It's ideal for building small circuits on a breadboard, and for exploring what different types of components like LEDs, buttons, and analog sensors do and how they work.

Just slot in your micro:bit and then hook up to its pins with a breadboard or by connecting jumpers directly. We've broken out every spare pin on the micro:bit that isn't shared with the LED matrix, so your projects won't interfere with the built-in functionality.

Features

• Comes fully-assembled and ready to use
• Pins exposed:
• 3V and GND
• Analog channels 0, 1, and 2 (these are the large pads on your micro:bit)
• I2C bus interface
• SPI bus interface
• GPIO pins 0, 1, 2, 5, 8, 11, 13, 14, 15, 16, 19, and 20
• Plugs straight into your breadboard (not included)
• Compatible with micro:bit (not included)
• No soldering required!