Workbench in the garage

I've been meaning for a while to set up a permanent workspace for doing electronics and finally cleared a corner of the garage.

Once cleared I of course needed a workbench and whenever I searched on line this steel bench kept coming up. Listed on the UK eBay for about £50 which to me seemed like an OK price to pay for a bench with main surface size of 120cm x 59cm and with a drawer the full length of the bench.

I asked on Twitter what it was like and a few people replied that the metal is quite light but it's sturdy once built.

I got one and for £50 I think it's definitely worth the price.

The metal frame is not the strongest or thickest metal I've seen and without the wood tops being in place it does flex. I expected to have to add braces at the side and back but in the end they are not needed as once the work surface and other wooden pieces are added it gets nice and rigid.

One thing to be aware of is the wood is MDF and so has limited strength in itself.

The lower shelf on mine is flexing already due to the boxes I have on it.  I note this in the video below and also my plan to add some wooden battens to support the lower shelf.

The lower shelf and the work surface are not screwed down and are held in by the frame so it will be easy enough to lift out the self add the battens and put the the shelf back on.

The draw was also pointed out to be quit flimsy and I agree. It's not robust but it works and for tool and storage for light parts it will do the job.  Again the base on the drawer is MDF.

The back pegboard on mine is slightly bowing out.  Not sure if I've done something wrong or if it's the kit.  The top shelf is OK.  Again I'm not expecting it to take much weight but as a place for odd small bits it will work well. It's also high enough above the main work surface that it should be ideal for adding additional lighting in the future.  Maybe some RGB LED strips 

Finally, the instructions are really poor.  The kit I received wasn't missing any parts but let's say with my flat pack skills it took me a fair while to get it all together. 

The one tip I'd give is watch the number of holes in the metal parts to figure out which way is up.

So, overall I'm very happy with the bench. I've used it a fair bit since getting it and I like the size.  Much smaller and it would be a challenge to have equipment out and have a decent sized work surface.  (There is a smaller sized version that's 81cm x 41cm and from searching eBay there are also versions without the back and top shelf.

Finally, here's a video of the bench so you can see what it's really like.

Onward and upwards with the making. 

More cheap stuff from eBay - Gaming Player Handheld Video Tetris Game Console Kids Children Boy Portable Toy

I'm drawn to the underside of eBay. The placed where strange bits of electronics are sold.  This interest comes from making things and needs odd bits of electronics to realise my (awful) creations.

On one of my regular trawls of ebay I found this.

Gaming Player Handheld Video Tetris Game Console Kids Children Boy Portable Toy

Looked interesting.  OK the display is obviously mono-colour LED and not back lit but for £1.39 I thought it was worth a punt.

From the Listing the dimension are: Product size: 14*8*2cm
Bigger than the Sony PSP Go 12.8*6.9*1.64cm
If Sony can squeeze a 4.3" widescreen display in the PSP Go then this could be a very useful case to work from. A nice sized case with 10 buttons.

For reference a Raspberry Pi Zero is 6.5cm x 3 cm.  An easy fit and with dimensions greater than the PSP Go one of the many 3.2" LCD displays I see running from a Pi should fit nicely.

£1.39 for a case with 10 buttons that should easily take a Raspberry Pi Zero and 3.2 " screen with space for other bits is a bargain.

I see a plan coming together so I ordered one two weeks ago and it arrived today.

The packaging is the same as the listing which is always a good start.

Opened the box and inside was the actual console. OK a bit rough and the sticker isn't straight.  Not a problem as I plan to remove all that anyway.

But there was something else not right.  I checked the listing again and confirmed the dimension Product size: 14*8*2cm

The dimensions on the actual one I received seem a bit off.  Annoyingly I don't have a ruler with me at the moment so I'm using AAA (not AA) as the standard measure.

An AAA battery according to Wikipedia is 4.45cm long.

From the picture below it looks like this may not be 8cm wide or 14 cm in length.

It is more like 9cm in length so a Raspberry Pi Zero may still fit inside and 5cm in width.
There goes the plans for a 3.2" LCD display. Maybe one of the  0.96" OLED displays might fit.


I almost forgot.  What about the 999 games.
It does have Tetris, a variety of Breakout games, a Tank combat game and a Driving game.

The driving game is especially bad as there are only 2 lanes and you just move from left to right as the cars come down the screen.

In summary how does it compare to the listing title.

Gaming Player Handheld Video Tetris Game Console Kids Children Boy Portable Toy
It is a game playing handheld video Tetris Game Console.
No kids, children or boys included, but it definitely is portable and a toy.

As an added bonus you also get the amazing driving game, breakout and tank combat games, so in a way it over delivers on the gaming promise.  I didn't count whether there are 9999 but I suspect we all know the answer to that.

But, if your reason for getting it is to have a 14cm x 8cm x 2cm case with an opening to put a 3.2" display and a Raspberry Pi Zero you will be very disappointed as it's most definitely a lot smaller than the listing.

It is held together with screws so maybe a teardown is needed to see what's inside and if there is anything I can salvage from it.



UPDATE:
I think I may have found an actual correct listing for the one I purchased
http://www.ebay.co.uk/itm/272730431909
Listing states the dimensions are: 10 x 4.5 x 2.4cm

Then there's also this listing for £1.79
https://www.ebay.co.uk/itm/222452404318
With the dimension listed as: 15.5*6.5*2.5cm

If the larger one really is those dimensions then a project may be on to use it as a shell for something more fun.

White Wii Nunchuck shaped Bluetooth Joystick - £1.85/£1.99 on eBay

When I attended PiWars (a great event for people who like to build robots using the Raspberry Pi) earlier this year I saw a whole range of controllers being used for controlling Raspberry Pi based robots. With many using USB dongle ones and others using Bluetooth or even apps on phones.  Expecting to see some BlueDot next year a great Android App for controlling things over Bluetooth.

Since my phone is iPhone (too long to explain) BlueDot isn't an option for me and with my continuing goal of finding cheap solutions to a problem I found a £1.85 Bluetooth controller from eBay - 3D Bluetooth Virtual Reality Glasses VR BOX Game Remote Control Gamepad Handles

What I liked about it is that it uses AAA batteries so if at an event the batteries died I could swap them out. No need to wait for recharging.

It's billed as being for mobile gaming and virtual reality and no mention of working with a regular computer or even Raspberry Pi, so I took a punt for £1.85, well actually £3.70, as I bought two. (walking on the wild side). 

eBay order confirmation

NOTE: The listing I bought from has ended but the same seller has a new listing at £1.99

I've seen some similar listing with switches on the side.  This is not the model I have bought. Mine has no switch.

What it looks like on eBay listing

They arrived and actually look good.  Plastic is definitely cheap, but they don't feel flimsy.
Below are a couple of pictures of the real thing.  A little different to the render but I'm happy..

Top. Joystick, power button, mode change button and 4 facing buttons.

Front has 2 additional buttons for when held straight rather than sideways

Time to start testing.

Setting up a new Raspbian image and using Raspberry Pi ZeroW I added the two AAA batteries and it came on. Blue light flashes to say ready to pair.

Using the Bluetooth Add Device in Raspbian the device VR BOX was found and paired successfully.  The unusal name actuallymakes sense as the listing on eBay is for "3D Bluetooth Virtual Reality Glasses VR BOX Game Remote Control Gamepad Handles"

Bluetooth on Raspbian paired with VR BOX

From the eBay listing and the single sheet of instructions the Gamepad/Nunchuck has 4 modes that you select with a combination of the @ and the relevant button.

A : Function Select (Music Video Mode.)

B : Function Select (game mode)

C : Function Selection (VR video self-timer mode.)

D : Function Select (mouse self-timer mode.)

It starts up in Music mode, so to use as a gamepad you have to change this after it pairs.

As I wanted to test in game mode I did [@]+[B]

I previously created a small python/pygame program to help with the testing.  It's available on GitHub.

I downloaded it to the PiZeroW (one of these days I'll do the proper git clone thing) and ran the program.

I run from the command line as the terminal window prints the details in text while the pygame window gives a graphic representation of the gamepad so I can see if multiple button presses are possible and which button numbers are pressed.  The code includes an analogue joystick so it will show the full range of movement for the gamepad joystick.

python2/pygame gamepad tester

Pressing the buttons the appropriate red square appeared and the terminal window stated which button was pressed or released.  Success! It's being detected as a gamepad and the buttons are working.

I then used the joystick which looks like an analogue stick you see on many projects. Only it's not. The joystick is digital.  Up, Down,Left,Right.  No range in values.  Except for a strange thing.
The positive values are 0.999969482422 and the negative values are -1, so you can't test for 1 for down and right when in gamepad (sideways) mode as 0.999969482422 is not 1. A little gotcha for coding.

The different modes

As listed above there are 4 different modes for the controller.

[@]+[A] for music
Nothing happened on the Pi. I haven't figured out what Bluetooth Music Mode is yet.
I tried this mode with my phone and it does provide volume up/down, mute an play so does what is expected with the target device.

[@]+[B] game mode
This is gamepad in horizontal mode, like a traditional controller with the joystick on the left and the buttons on the right.
For example, if you push up the Up joystick is detected

[@]+[C] VR video self-timer mode
This is a gamepad in Nunchuck mode. So vertical.
For example, if you have the controller held vertically and press up then Up Joystick is detected.
All the buttons are the same as for game mode.

[@]+[D] mouse self-timer mode
Guess what the joystick operates like a mouse held like a Nunchuch (vertical) with the lower front button (trigger) being left click and the higher front button (trigger) being right click.
In mouse mode buttons A and B still get recognised as gamepad buttons so that could be useful.Not sure how or when but extra buttons are always useful. 

Button combinations

In game mode some of the buttons could be pressed at the same time while others could not.

@ and Power are reserved so have no button function.

Bottom trigger and top trigger could not be pressed at the same time. Lower trigger always took priority even if upper was pressed first.

Bottom trigger could be pressed with any of the face bottoms (A,B,C,D). Same for Top Trigger.

A could be pressed with C, but not B or D. A stays active and the others do not show.
If you press B or D first and then press A, A will be activated and the other will be released.

B and C can be pressed at the same time

D is over ridden by all face buttons, so if you have D pressed and then press any of the other their function is activated and D is released.

Also, either trigger and two button face combinations that were noted to work above will also work.
So, if you need 2 buttons at the same time and one is the master and the second one needs to be one of 4 I'd recommend using a trigger as the master and the face buttons as the secondary as this works for all face buttons.
If you need 3 buttons then there are a small number of combinations that will work.
Top button, A and C worked for me.

Future Note: I have a feeling this section may need a chart of some nature. Need to figure out how to represent it.

For Python/Pygame and I expect other system the buttons are numbered:

Gamepad Mode


Face button arrangement
  A 
C   D
  B


Top Trigger: button 7
Bottom Trigger: button 6
A: button 4
B: button 0
C: button 3
D: button 1

VR mode (Nunchuck)

Face button arrangement

  C

B   A

  D

Top Trigger: button 7
Bottom Trigger: button 6
A: button 1
B: button 3
C: button 0
D: button 4

When I saw it changed I thought the button values would have turned clockwise 90 degrees so the buttons were in the same position (top, left, right, bottom) would have the same values but they don't. Top and bottom shift correctly, but left and right are mirrored.

Where did 2 and 5 go.  I wonder if they're on the board and not broken out. Might be a tear down thing

Summary

For £1.85, or £1.99, last time I checked if your need is digital controls then I think this is a hit.  It paired easily. The instructions though really sparse are enough to change modes.
With a phone it does the media things promised from mode A and on the Raspberry Pi and expect and device that supports a Bluetooth Gamepad and Mouse it does exactly what it says on the tin.

For controlling robots it's ideal (except for no analog).
Joystick for direction control and then buttons for other functions. Maybe take a picture, fire a missile, change mode from piloted to auto mode for different challenges at an event like PiWars.
With the advantage of using regular AAA batteries there is no fear that at an even the controller will run out of power and need to be charged.


A little but extra

As each controller having a unique Bluetooth Device ID it's possible to set up a cronjob on Linux to  pair with a specific gamepad when the Raspberry Pi (ZeroW) is booted/rebooted so  at events if you had 5 robots, 5 controllers each controller would be set up to work with a specific controller
It's not too complicated to do.

Get the device ID for the VR Box using the command bluetoothctl
Mine was FF:FF:70:00:76:8B

Run crontab -e
Select your editor if running for the first time. I use Nano

Go to the end and add the line

@reboot echo "connect FF:FF:70:00:76:8B" | bluetoothctl

If using Nano do a [ctrl]-[x] to exist and 'y' to save.
Reboot an you're done.

This will try to auto pair when the Pi boots.

You can also do a cronjob to continuously try to reconnect and not just at boot.
This is useful if the Pi has completed booting before the gampad has been turned on or if the controller hasn't been used for 10 minutes or in pairing mode fails to pair after 3 minutes and so needs to repair when the controller is turned back on

eBay USB soldering iron in use

Sometimes I've to do a little bit of soldering.  Usually only a few wires and since at present I have no place to leave an iron set up permanently this requires for me to either unpack my rework station or even just a simple mains powered soldering iron.
Even doing this has resulted in me pushing back soldering jobs as the extra time for setup
 as a ratio against actual build time doesn't feel like time well spent.

Then on eBay UK I came across a listing for USB soldering iron for £3.39

Since my electronics is usually tied to an Arduino or Raspberry Pi project I will have a computer up and running and I thought for less than £4.00 including shipped from Hong Kong it was worth a punt.
Well, it arrived this week and as per the picture it includes the soldering iron with a plastic cover for the top.  A USB to 3.5mm jack for power.  A really small stand made from a folded piece of metal with a bit taken out and just enough solder to know it's working.  Actually I soldered about 30 wires using the solder provided and have a bit left over.  Still you'll need to get some solder.

First impressions were positive.  Packed in a proper retail packaging box and not just a jiffy bag like many cheap things on eBay from Hong Kong.

The iron heated up quickly and has a red LED to let you know it's on.
It was definitely hot enough to melt the solder and do the job I required.
Since the original outing I have used it again to replace some current limiting resistors for 5 LEDs in a project I'm working on.  Again all worked great.

As I've only used it twice I can't speak for the long term reliability but from first impressions it is well worth the £3.39 it cost me.

The only things I would change are:
I would have liked the power to be microUSB and not 3.5mm jack.  I've loads of microUSB cables but this is my only USB-3.5mm cable.  If I lose it I'll have to get a new kit. Probably not a disaster at £3.39 and then I'd have a backup.

The tip on the iron is a needle tip. My personal preference is a bevel tip. The ones where it's like they cut a diagonal slice off a flat tip.
Here is a nice instructable explaining the different tips. My preference is called a C series tip in the guide.   Rarely do really fine work and even then a bevel can still be used quite well for most things.

Saying all this for less than £4.00 it feels nice to use and means I can set up, do the rework and pack away in minutes. Which is ideal when only soldering a few wires at any one time.

UPDATE: after posting this I was sent a link to a great video by bigclivedotcom where he tests, tearsdown  reverse engineers the circuit diagram.  Let's just say his review is way better than mine.
Here's the video.

RGB LED pixel ring with Raspberry Pi, Crumble and CodeBug

I've seen the Adafruit RGB LEDs in a number of projects and thought they were very cool. From doing some research they are controlled using a WS2812 and there are a number of sellers selling strips and rings based on the same driver and RGB LEDs.

On a recent trawl of eBay I came across the following RGB LED Ring 24 Bit WS2812B 5050 RGB LED with Integrated Driver 

24 pixel RGB LED ring

When it arrived I'd to solder a few wires to it.  5V, GBD and DI (in).  These pixels are controlled using a custom one wire protocol, so all 24 or more LEDs can be controlled with 1 pin.  There is also a DO (out) which allows you to chain the rings. Taking the DO from the first and attaching to the DI of the second.

Over the past year I've acquired a Crumble and a CodeBug in addition to the Raspberry Pi
Both the Crumble and CodeBug use a block based programming system and have the ability to control RGB LEDs, so to test the ring I started with the Crumble as it was nearest to me. I put together a short little program and it worked.  The code below is v2 with a small animation on collision.  For the Crumble it's connection D that you attach the LEDs to.

Crumble Code

Once I was sure it worked I noticed that CodeBug had an RGB LED example that I hadn't seen before. They call them GlowBugs. The web interface has the option for enabling the Star which attaches to the header and 5 or 10 GlowBugs. I enabled 10, did the code to make 10 change colour and it worked perfectly.  The great thing with the CodeBug is it is programmed using a web interface, nothing to install. When you do a download you just drag and drop the file to the CodeBug which is seen as a drive and that's it. No drivers or funky settings needed.

Since I had nothing to lose I set the counter to 24 to see if it would drive all 24 LEDs. Again success. So, the CodeBug can handle more than the pre-selected 10.  For the CodeBug it's connection 3 that you attach the LEDs to. You have to click the cog in the emulator  pane on the left and enable the GlowBug for them to work.

CodeBug Code 

That's 2 platform down.  Just the Raspberry Pi to go.

As mentioned above the protocol for these LEDs is custom and my understanding is timing specific and so getting it to work on the Raspberry Pi may be more difficult.

Then Twitter and the great +ForToffee  came to my rescue. with the following Tweet.

@AverageManvsPi @winkleink not sure where you got up to with this. Install the UnicornHAT library then you can use WS2812 library

— Carl Monk (@ForToffee) December 13, 2015

So, the UnicornHat from Pimoroni also uses the WS2812, brilliant. These guys usually have good libraries and code so I found it on GitHub. 

From the README.md I used the curl command to do the install.

\curl -sS get.pimoroni.com/unicornhat | bash

This was on an updated Jessie on a Raspberry Pi 2 and it installed perfectly.

I went to the examples folder and ran demo.py.  This is expecting an 8x8 matrix, but even on a 24 pixel ring it looked great.

One thing not noted, pr that I couldn't find is that the LEDs are connectioned to BCM pin 18, the hardware PWM pin.

Once it worked I then had to figure out how to address each pixel individually. 

As you'd expect the UnicornHat code is all designed for an 8x8 matrix and not a circle, so running the LEDs from 1-24 caused the actual LEDS to light up out of sequence..I thought I was going to have to do some kind of look up to match the X,Y for the matrix code with the individual LEDs but then looking at the GitHub repo there was more details on the WS2812 code.

At the bottom of the README.md was the following reference.

Based Upon rpi_ws281x

Unicorn HAT is based upon a modified, Pi 2 compatible version of the RPi ws281x Library by Jeremy Garff.

The library was modified by Richard Hirst.

• Modified version: https://github.com/richardghirst/rpi_ws281x

So, I checked Richard Hirst's GitHub and found an example that didn't look too complicated.

https://github.com/richardghirst/rpi_ws281x/blob/master/python/examples/lowlevel.py

OK, at first sight it looked complicated, but after reading it a bit I figured it out.

Colours are done in HEX

Line 16 in the code sets the number of LED. I changed this to 24 and ran the code.
Worked first time.

Looking at the code again.

Lined 25 - 35 are just setting up some preset colours.  

So, change line 16 to set the number of LEDs and lines 25-35 if you want to pre-set colours.

Other than this all code up to line 67 doesn't need to be touched.
It just works and my motto is if it aint broke don't fix it.

The try: just cycles through the LEDs setting their colours 

The two key commands in this block are. 

ws.ws2811_led_set(channel, i, color)

This sets a colour for LED i (Note LED numbers start from zero)

resp = ws.ws2811_render(leds)

This command actually does the setting.
So, if you want to change a number of LEDs at the same time use the ws.ws2811_led_set command for each LED and then run a single ws.ws2811_render command to actual set the LEDs.

After modifying the code I could control each LED.

In summary these RGB LED rings work just like Neopixel with the WS2812 driver. 

They work great with Crumble, CodeBug and Raspberry Pi. Coding is easy and special set up is only required for the Raspberry Pi, but with the UnicornHat library install it's really easy to get working with python.

Note:

These LED rings if driving a lot of the LEDs with bright colours can use a lot of power. I'd recommend powering from an external 5V supply. The Crumble specifically will not power them from the USB through the Crumble.
I have a Crumble battery holder for 3 x AA batteries that I used for each of the setups to power the LEDs, For the Crumble and CodeBug the batteries also powered the boards as well.  While for the Raspberry Pi I used an external 5V supply for the Raspberry Pi and the batteries for the LEDs making sure to connect the ground pins together to ensure that the whole circuit has the same GND reference.
I don't know how the actual UnicornHat powers the LEDs when on the Raspberry Pi

Side Note:
I haven't tested with Arduino yet, but since these things have been controlled by Arduino for years already I expect it to just work.  I have a Digispark ATTINY85 that is really small and is suppose to work as well since it's basically a minimal Arduino compatible.  So, will give that a try.

Robot Club - first session completed

Link to Previous Post on Preparing for the Club with details on Partner Used: http://winkleink.blogspot.co.uk/2014/11/preparing-for-2015-after-school.html


Today we had the first session of the new robot club I'm running at my kids primary school.
It is for year 6, so 11-12 year olds.

The club is based on the parts from the previous post. http://winkleink.blogspot.co.uk/2014/11/preparing-for-2015-after-school.html

Today the kids came in and there were 3 from last year, so 7 new which is great.
Also, the gender mix is 4 boys and 6 girls.  Sounds very positive from a gender equality then heard the robot club is clashing with football, so expect there are many boys already committed to football.

Still it was a great first session.

The goal for today was to build the chassis.  I wanted to give the kids a bit of a challenge so we worked it out together using the Chinese instructions and my previously built chassis.

A lot of bolts going in the wrong way round and parts in upside down. So, each team had to take their bits apart multiple time.

As we went through the hour I expected the kids to lose heart with the every increasing times they had to remake the chassis.  But, I was delighted that by the end they were very excited to have it built and really wanted to do more.  We had to stop as parents were waiting to collect the kids.

We wired up some of the motors and I showed that since the motors mirror each other than with the motors wired the same way that one wheel goes forward and the other goes backwards with the same red-positive / black-negative wiring.  I explained we can sort this out in code.

The best comment of the day from one of the girls was. "Today is the first time I don't want to leave school."

She was very curious about the 4x4 keypad, so I explained how it works.
Send a signal into each horizontal pin one after another and seeing which pin it comes out at.

Metal Note: try to bring a white board market next time.  Teachers take them away after their classes.


In preparation for next week I have to get all the chassis sorted. One of the motors had the tab ripped off so lucky I have a spare motor.

Then add the L298N H-Bridge and Arduino Nano compatible so coding can start next week.

Goals for next session.
Understand the wiring.
Code to make it go forward, backwards and turn.
Program to go around the centre section in the room.

Roll on next Monday.

Raspberry Pi model B+ composite/RCA video/audio adapter

With the release of the Raspberry Pi model B+ the previous arrangement from the A/B of having a 3.5mm stereo audio jack and an RCA for video has been changed to a single 3.5mm jack that includes stereo audio and the composite video.

I kept reading online that the arrangement was the same and the iPod and also the Zune so there are loads of cheap cables and adapters out there that work.

After lots of searching I found a number of cables that looked like they would work, but since they were all cheap no specifications for the wiring were listed.

From the Schematic (http://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/Raspberry-Pi-B-Plus-V1.2-Schematics.pdf) the arrangement needed from tip to base is.

Tip - Audio Left
Band 1 - Audio Right
Band 2 - Ground
Base - Composite Video

It doesn't really matter if the audio connections are reversed as you could just swap the leads, but getting the ground or the composite in the wrong position means no video would be output and in the case of ground no audio also.

So, I went mad and took the plunge to buy a £2.00 adapter from eBay and see if it works.

Here it is plugged into the Raspberry Pi Model B+

RCA/Composite video adapter for Raspberry Pi B+

It covers the HDMI port which isn't a problem. As, when I'm using composite I'm not using HDMI.

I am delighted to say it works perfectly. The wiring is correct. I plugged it into a television and up popped the display from my RetroPie install. Playing Double Dragon on the big screen.

Double Dragon played over composite with stereo audio

The price was only for the adapter, but I had an RCA cable from my kids Karaoke machine, but if you don't have one handy then this one for £1.99 also from eBay would work.

Meaning for £4.00 all in you  have an adaptor for B+ to connect to composite and analogue audio as well as the required connecting cable.

I like that it is a 2 piece configuration as a composite cable can have other uses.  I spliced one before to work with an Arduino and the TV-out Library.

Gathering more bits.