Author Archives: paul

Controlling a 28BYI-48 stepper motor with Wifi for less than 10$ USD by using an esp2866 12-q

For low cost robots, remote controlled laser pointers, cat or fish feeding machines I found a really cheap way to move things by programmable wifi. The already handy usable 28BYJ-48 coming small motor driver i board is available in china for about 2$. It additionally needs to be driven by a fast micro controller like the Arduino or the much more capable Raspberry Pi. As I was experimenting with the esp2866 12-Q recently, the combination of this two useful things seemed more than obvious. Therefore I decided to give it a try.

Unfortunately the stepper motor and its driver chip the ULN2003a need at least 5Vs to run, a voltage the esp2866 would by killed by as its maximum rating is about 3.6. in conclusion two power circuits or two power sources would be required. I tried to keep things simple by using an 5V-12V power source and step down converting it to 3.3V with an lm2655 based step down circuit. This setup allows an efficiency about 95% and avoids producing high amounts of heat as linear step down converters would have done. Overall the motor and the controllers consume 0.35 Amps at 5V therefore about 1.75 Watts.

: 28BYI-48 stepper motor with Wifi – esp2866 on breadboard adapter

: 28BYI-48 stepper motor with Wifi ULN2003a driver board

: 28BYI-48 stepper motor with Wifi – final setup

: 28BYI-48 stepper motor with Wifi -final setup 2

: 28BYI-48 stepper motor with Wifi – final setup 3

: 28BYI-48 stepper motor with Wifi – final setup 4

Parts

2$ 28BYJ-48 with ULN2003a motor driver
2$ esp8266
2$ step-down-converter
> 0,5$ breadboard 2.5 mm adapter for the esp8266
> 0,.5$ for15 cm of additional cables low diameter
soldering equipment and an 3.3V FTDI Adapter for flashing the esp2866

Steps to build your own:

solder the esp2866 on the adapter board
reverse the in1 in2 in3 in4 pins to the other side of the motor driver ULN2003a board
put the breadboard adapter on this pins starting with vcc followed by in1 to in4
connect the v_out of the step down circuit with vcc of the breadboard adapter
connect v_in of the step down circuit to the vcc of the motor driver board
connect all GNDs together
add pins on the breadboard adapter for flasingh the esp2866, GND, VCC, TX and RX
flash the esp2866 with
https://github.com/PaulPetring/esp2866-28BYJ-48-motor-control/blob/master/simple.ino
test solderinng and apply between 5V an 12V connected to the motor driver board
have fun 🙂

Wiring concept

Video on Youtube

https://github.com/PaulPetring/esp2866-28BYJ-48-motor-control

VW T4 Project – secondary battery

To supplement my electronic needs like running my laptop during my journeys I recently added an secondary battery to my VW T4 Project. There a several ways to connect the second battery like wiring it in parallel to the main battery, charging it separately by socket, using an solar panel with charging controller or the way I decided to do: using an uncouple relay to load the battery only while the generator of the motor is running. To realize this, a decouple relay and a trigger signal is required. Also some fuses and really big diameter cables are needed to prevent voltage losses and avoid overheating while transporting drect current two or three meters through the car.

decoupling relay scheme

Charging

The main wiring is hidden beneath the drivers seat, here you can see the relay and one of the 40Amps fuses.

VW T4 Project – secondary battery – uncouple relay beneath the driver seat

The battery itself is located in a wooden construction directly under the drivers seat. It is an absorbent glass mat model, which is capable of being loaded 5 times faster than regular car batteries without loosing current level over time. Furthermore it is well suitable for a solar setup. Deep discharging (or lets say below half capacity measurable at 12.5V) without ruining the battery is possible but significantly shortens it’s lifetime. One more thing to mention is the different voltage level of the battery, fully charged it completes at 14.4-14.8 Volts, a voltage the main generator is not capable of delivering, and also stresses the main battery which is not of the same type.

VW T4 Project – secondary battery – absorbent glass mat 80Ah

To trigger the relay to wire the two batteries in parallel only when the main generator provides at least 13.9 Volts (or up to 14.3V depending on headlight or fan status) I searched for a suitable D+ wire in the central electric. D+ is a signal provided by the generator, which provides 0V while the ignition is off. If the key gets inserted and turned until all lamps turn on, but the motor isn’t started yet it should provide about and below 10Vs. Only if the charging regulator of the car has been triggered which usually happens when the number of revolutions hits above 2000 it should provide the Voltage of the generator. Took me several hours to find the right cable, because for some reason all light blue cables (which should have this properties according to my sources) didn’t behave as expected. Finally I found a dark blue and black striped not used cable of the relay board as you can see in the pictures below:

: VW T4 Project – secondary battery – central electric

: VW T4 Project – secondary battery – central electric – back

: VW T4 Project – secondary battery – not D+ but behaving like it

Controlled Discharging

At this point the secondary battery gets charged while driving, but there was no way to plug any 12-14V devices to a car lighter jack. Therefore I built one:

: VW T4 Project – secondary battery – wooden constuction between front seats

: VW T4 Project – secondary battery – wooden constuction between front seats switched on

Avoiding deep discharge I planned to use a battery guard device which turns of discharging when a certain amount of voltage gets undershot for a certain amount of time. Unfortunately my absorbent glass mat battery is incompatible to most of these devices as its half capacity voltage is much higher than that of usual car batteries. I found a programmable device that sadly arrived broken and therefore couldn’t be added to the current setup. To oversee the voltage and discharging current at least somehow, I’ve added an digital volt and ampere meter and wired it including an switch to turn it off at night:

VW T4 Project – secondary battery – back wiring

As you can see it uses a shunt to – lets say guess – the current drain. Furthermore I’ve added an 20A fuse. I used a piece of electric cooker wire and fused two pairs of wiring harness together to increase wiring diameter and prevent voltage drop. The third harness is left unused.

For now this setup allows to use my laptop which drains about 10 Watts on power-safe mode for 10 hours per 100 kilometers driven distance. This of course gets limited by the size of the generator, driving style and battery capacity.

Anyways, this setup somewhen will be supplied by a solar panel to charge the battery to full capacity in summer by the sun, and charge it at least a bit by the generator in winter. Keep in mind that solar power and decoupling relay in combination with an absorbent glass mat battery could not be used in parrallel due to the different voltages of main generator and full capacity agm battery.

Connecting a Raspberry Pi 3 to Wifi and add defaults

Connect the Raspberry to an existing local area network by cable.
– I used the Ubuntu “Shared to other computers”-Network manager Setting to bridge my eth0 to my wlan0 connection providing internet access.
Connect via ssh to this device
– username: pi
– password: raspberry
– usually you don’t now the ip of the device use nmap 10.42.0.0/24 -p 22 to search for open ssh devices
Scan for local wifi networks: sudo iwlist wlan0 scan
sudo nano /etc/wpa_supplicant/wpa_supplicant.conf and add your wifi connection data:
```
network={
    ssid="networkname"
    psk="password42!"
}
```
restart the wifi and bring it to connection sudo ifdown wlan0 && sudo ifup wlan0
Get the latest software status lists: sudo apt-get update
Update all installed software: sudo apt-get upgrade -y
Install common software to harden the system:
sudo apt-get install x11vnc htop bmon fail2ban vnstat ufw
– x11vnc: nice tool to use VNC connections on the main x session
– htop: visualizes processes and load in color
– bmon: visualizes network traffic
– fail2ban: handles bruteforce attacks by banning Ips for a certain amount of time
– vnstat: counts network traffic over time
– ufw: makes it easier to handle ipables and configure your firewall
Start the Raspberry Pi 3 Configuration Programm: raspi-config
– expand file system to match your sd card size
– set hostname in advanced settings
enjoy your new Raspberry Pi 3 \o/

: Raspberry Pi 3 Model B+

: Raspberry Pi 3 Model B+

: Raspberry Pi 3 Model B+ 4 USB Ports

Presentation BHT 2016

I will hold a small presentation about Low-Cost in a Robotic-Context at the BHT 2016. It will start at 17.00 at the Helmut-Härtig-Building of the Technische Universität Bergakademie in Freiberg.

Links:

Slides

in german, due to copyright, I removed some of the pictures:

VW T4 Project – War against Rust – Battle V – Sill Part Two

As I learned recently stick electrodes are not suitable for welding thin sheet metal of a cars body shell. The electrodes tend to burn holes instead of welding anything together. Unfortunately, all other welding techniques like MAG,MIG, WIG (TIG) welding, require expensive hardware and some degree of education. After some research I found a rent-able workshop including hydraulic lifts, all kinds of tools and MAG-Welding equipment for 8€ an hour. After some practice welding on small pieces of steel, I felt confident enough to start handling the spots i prepared as described in part one:

: VW T4 Project – War against Rust – Battle V – Sill Part Two – welded sill

: VW T4 Project – War against Rust – Battle V – Sill Part Two – weldet sill top

: VW T4 Project – War against Rust – Battle V – Sill Part Two – added putty

: VW T4 Project – War against Rust – Battle V – Sill Part Two – more sanding and fertan

: VW T4 Project – War against Rust – Battle V – Sill Part Two – undercoat

: VW T4 Project – War against Rust – Battle V – Sill Part Two – some layers of paint

: VW T4 Project – War against Rust – Battle V – Sill Part Two – final result 1

: VW T4 Project – War against Rust – Battle V – Sill Part Two – final result – as good as new

: VW T4 Project – War against Rust – Battle V – Sill Part Two – final result as good as new

To improve the durability of the inner surfaces I used a new rust converter called fertan. As research has shown it is used by a lot of car restaurateur workshops and is quite effective protecting the metal from new rust by creating an protective coat. After 24 hours of letting it dry I additionally added another new rust preventing oil: Owatrol. It’s a synthetic resin based oil able to prevent rust to grow by cutting it off from water and air. By that, the spot should hold 2-3 years without replacing the complete sill.

First welding experiences!

I could manage to buy a cheap welding helmet with automated darkening feature! I already owned a cheap welding electrodes setup an therefore was allowed to take some training welding today:

First welding experiences – top

First welding experiences – bottom

First welding experiences – top 3

This small welding worms are really not worth mentioning in a welding context, but for me, this is a real achievment of working with metal. With that ability I’ll soon be able to fix the sill issue on the front left door 🙂

VW T4 Project – Interior construction – Realization

The step after planning is realization, so I went to the local home improvement store and bought some sawing rough wood at 3,69 € per meter. I additionally required several M10 screws at 90mm length for assembling the wood construction directly to the ground floor of the VW T4.

: VW T4 Project – Interior construction – Realization – Carpet with newly zinced rusting spots

: VW T4 Project – Interior construction – Realization – first wood construction

: VW T4 Project – Interior construction – Realization – first wood construction assembled

: VW T4 Project – Interior construction – Realization – further wood assembly

: VW T4 Project – Interior construction – Realization – further wood assembly 2

: VW T4 Project – Interior construction – Realization – further wood assembly 3

: VW T4 Project – Interior construction – Realization – rust converter bath for some rusty parts

: VW T4 Project – Interior construction – Realization – first beddinge test

: VW T4 Project – Interior construction – Realization – beddinge missing some pieces

: VW T4 Project – Interior construction – Realization – final assemlby

: VW T4 Project – Interior construction – Realization – final assemlby – better than expected!

: VW T4 Project – Interior construction – Realization – right side with sketchup model on laptop

: VW T4 Project – Interior construction – Realization – back with full bed

: VW T4 Project – Interior construction – Realization – current untidy status

Thanks to my going-to-be-brother-in-law for all the help during the wood construction progress! I am totally surprised by the high level of functionality and very low cost for the interior simply by combining the given circumstances.

I have already spent two nights inside and do not miss any functionality of the bed and couch at all, it’s way better than I could imagine 🙂

VW T4 Project – Interior construction – Planning Stage

Usually it is really helpful to take a decent time to plan the interior design, but due to my available going-to-be-brother-in-law
for one day, I had to do this at night during my well deserved sleeping time. Taking the measures from the carpet I came to this Sketchup model:

VW T4 Project – Interior construction – beddinge as a couch, having 5 cm left as a 1,95 cm guy while sitting

VW T4 Project – Interior construction – right side view – top rectangle is roof

Fortunately at this time I had a left over sofa-bed from IKEA called Beddinge around, which I would like to include into my interior design. It is foldable and usable as a couch and therefore perfect as a the heart of my low cost campervan VW T4:

It is possible to pull the seating area and get an full 140 by 200 cm bed by that:

VW T4 Project – Interior construction – front right view

VW T4 Project – Interior construction – back right view

VW T4 Project – War against Rust – Battle VI – Interioir

As presented in a previous post, my beloved Vw T4 has some Issues with rust on the interior floor. For some reasons I will explain soon, I only got one night to solve these and handle all spots below the carpet as good as possible.

This is where we have to start:

VW T4 Project – Interior construction – Removal of all Seats – looks like an area needs to be treated

I forgot to take the right amount of progress pictures but some can be shown here:

: VW T4 Project – War against Rust – Battle VI – Interioir – Carpet cleaning with spiritus

: VW T4 Project – War against Rust – Battle VI – Interioir – carpet sealing with duct tape

: VW T4 Project – War against Rust – Battle VI – Interioir – after two layers of rust removal

: VW T4 Project – War against Rust – Battle VI – Interioir – from the side

: VW T4 Project – War against Rust – Battle VI – Interioir – from the back

: VW T4 Project – War against Rust – Battle VI – Interioir – from the back further

: VW T4 Project – War against Rust – Battle VI – Interioir – couldn’t manage to fix the hole in the right back properly due to time restrictions

: VW T4 Project – War against Rust – Battle VI – Interioir – right side

: VW T4 Project – War against Rust – Battle VI – Interioir – most rusted spots after treatment

it is really time to learn to weld and to plan the interior functional design.

VW T4 Project – Interior construction – Removal of all Seats and carpets

I currently do not know anything about the status of my VW T4 interior. Is there rust? Do I need to fix anything before starting to convert the interior to fit the local camper regulations?

Only one way to find out, therefore I started by removing the seats: