How to add a LiPo battery in our Arduino projects

In the next Bike Pixels version I want to integrate a rechargeable battery so you don’t have to rely on an external power source. In principle, this might seem trivial, but it’s not. Lithium-polymer batteries (or LiPo) are very dangerous if they are incorrectly charged, overcharged, overheated or stored incorrectly they can explode. Luckily to make things easier for us and allow us to use a LiPo battery in our Arduino projects we have several modules that can do some of the work for us. One of these modules is the TP4056.

TP4056 module specs

The main element of the module is the TP4056 chip itself. This chip is a programmable linear current and constant voltage charger for single cell LiPo batteries. The module also integrates two LED indicators of the state of charge and two additional chips in charge of the protection of the battery. Although there are versions of the module that do not have these chips, in this case we will use a version that does have these elements like the one described in the image.

TP4056 module Components
TP4056 module main components description.

The module performs the charging process. First it ensures a constant current until the LiPo battery reaches 4.2V. Then, it gradually reduces the charging intensity until the battery is fully charged and ends the charging cycle when the charging current drops to one tenth of the programmed value. It supports input voltages up to 8V so it can be used directly connected to a USB port or a mobile charger up to 1.2A.

(more…)

Advantages and disadvantages of Arduino clones

One of the first things we should do when we start a new Arduino project is to look for a free board. Then we have to disconnect what we had on the board to make room for the new development. Of course, the ideal would be to have a couple of dozen Arduino boards, but that would cost us a small fortune. Luckily we have the possibility of using Arduino clones although these have some advantages and disadvantages.

Arduino Nano original and its clones.
Original Arduino Nano (left) along with two clones. The middle model is the one that includes the first prototype of Bike Pixel Rear. The one on the right is totally modified being all the elements on one side so it is the least thick.

During the project I used both original plates and clones. In testing and developing the prototype, I used an original Arduino UNO board and a Nano. For the final assembly of the prototype I opted for a clone, directly soldering the connections and components over it. This choice was due to the fact that the original Nano plates include by default welded legs. In our case this was the first advantage of the clone board but can be also a disadvantage as the welded legs facilitates the connection with other elements and we can do without the welder.

(more…)

Bike Pixel with Open Hardware certification

Bike Pixel is now officially a project certified by the Open Source Hardware Association (OSHWA). The mission of this non-profit organization is to foster the creation of open source and free hardware. To this end, it annually organizes different events such as the Open Hardware Summit or the Open Hardware Month. Additionally, they issues its own Open Hardware certificate and maintains an archive with all certified projects.

Certification stamp of the Bike Pixels project.

The certification offered by OSHWA ensures that a given project publishes all its source files using open licenses. That guarantees that all the elements that compose a design can be used freely to recreate and modify the project.

(more…)

Where to buy Bike Pixel Rear components

Before we start building our Bike Pixel Rear prototype, we must have all the necessary components. The prototype version (or v0.x) is the one that requires the least number of elements and therefore is also easier and cheaper to assemble. Below I leave you the complete list of elements along with links to different online stores where you can buy the components:

ComponentAmazon.co.ukAliExpress
Arduino Nano (Clone)£5.99 1.76 €
8×8 NeoPixels flexible matrix£34.1510.47 €
3 x touch switches (6x6x8mm)£2.95 (100 buttons)1.50 € (50 buttons)
3 x 10 kΩ resistors£1.59 (100 units)0.86 € (100 units)
1 x 470 Ω resistor£1.69 (50 units)0.86 € (100 units)
9 x 1.6M 10 mm to 12 mm screws£6.25 (100 units)1.56 € (50 units)
4 x 1.6M 4 mm screws£4.59 (50 units)1.53 € (100 units)
13 x 1.6M nuts£2.58 (100 units)1.46 € (10 units.)
1m AWG 24 cable (0.51 mm)£9.99 (5x9m)0.92 € (130 units)
1 x 1000 uf/6.3V capacitator (optional) £5.51 (20 units)1.68 € (50 units)
1 x 6 AA battery holder (optional)£2.692.15 €
6 x rechargeable AA batteries (optional)£9.99 (8 units)6.28 € (8 units)
1 x on\off botton (optional)£0.75 €
1 x 10000 mAh PowerBank (optional)£10.79 €
(more…)

First Bike Pixel Rear prototype ready

After a few weeks of planing, coding, proofs and tries and retries I’m pleased to announce that the first prototype of the BikePixel Rear is ready to go.

First BikePixel Rear prototype.

This version is based on Arduino Nano (actually a clone ;), our own PCB and a couple of other components (more information in the GitHub repository).

(more…)

Custom PCB layout in Fritzing

During the development of Bike Pixels we are using Frizing to design all sketches and PCBs. In some cases, like during the creation of our prototype of the BikePixels Rear, you may want to use a custom shape of a PCB instead of the default rectangular shape.

Image of a custom PCB design in Fritzing
BikePixel rear prototype custom PCB design loaded in Fritzing

Fritzing enables to import custom designs of boards based on vector SVG images. Basically the process is divided into two main steps. First it is necessary to create your own board design in a vector drawing application like Inkscape or and after that you will want to import this design into Fritzing.

(more…)