Design a raspberry Pi HAT shield

Raspberry PI Shiel Hat standard
Raspberry PI Shiel Hat standard

When you want to design a shield for Raspberry Pi, you have to follow the HAT standard. This standards describes the form factor of the shield to ensure future compatibility. It also describes the configuration solution for the board based on a flash containing necessary information. The Hat standard link gives all the detailed specification to design a such shield. In this post I’ll describe my experience of designing such shield and you will find the basic elements I build and now sharing with you.

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I2C activation on raspberry PI B+ and 2

The new version of kernel now activate the device-tree standard, it means that instead of having all module activated by default with some stopped by a blacklist system, now, all are disable and activated only when described in a device tree.

Device tree details the system architecture and dependencies following configuration files. The device tree can be owned by the shield itself in an attached eprom.

As a consequence, now, i2c / spi are not activated by default. So if you need to activate it on startup. For this, edit /boot/config.txt and add line at the end like :

dtparam=i2c_arm=on   # for i2c 1
dtparam=i2c_vc=on    # for i2c 0
dtparam=spi=on
dtparam=i2s=on

dtparam=i2c_arm=on,i2c_vc=on

Then reboot

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Add wifi to an arduino for 4€ with an ESP8266

esp8266 wifi for arduino
esp8266 wifi for arduino

The ESP8266 is a simple standalone addon for any board that works fine with Arduino and only cost less than 4€ on ebay.

It can operate as a device or an AP can gives wireless network connectivity to your application. It is interfaced with Arduino based on a serial line. The only problem of a such thing ( as for most of wifi chip ) is the power consumption. It requires about 150mA to run ; a lot for batteries.

My Friend @couac made a really good post on how to make it working with a Yabas, basically any Arduino board, I recommand the reading of his post : william post on ESP8266

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Sigfox Rf test first experience

This morning, some colleagues helped me to test the rf performance of one of my sigfox tracker. I’m really not an RF expert, I try to improve but there still be a long way to go…

In this design I’m using a TD1204 and a Wurth smd 868 antenna ; I have a 100 ohm impedance net between both (sure it is bad) and LC circuit (that sound not to be the good one – btw).

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Tobeca 3d printing settings for PLA

After some month of use of the Tobeca printer and a lot of time spent to find the right settings, this post is summarizing my experience. I mostly worked with PLA because I was not really fan of using acetone and abs+ acetone mix on a 80°C heating plate, so I’ll not yet detail how to setup ABS, but why not later. So this post is about PLA, about temperature, about adherence and Repetier settings.

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Baku 702B soldering station – change your soldering iron head

BAKU 702B Soldering Station
BAKU 702B Soldering Station

I wrote a post about the baku 702B 6 month ago with my initial feedback after receiving it.

After 6 months, my feedback is good and the station works well. I just made 45 raspberry shields with it using the air flow and the soldering iron and it make the job.

Now it is time to change the soldering iron head. For sure its life has been short compare to my previous one from another brand. My fear was to find a compatible head as I saw none of them with the 702B reference.

The solution is to search for 936 – 937 station or Tip 900M, they all are the same and works well with the Baku 702B. Go on ebay and pay 1/2€ each ; you will also find different head type. I recommend to order some right after buying the station as they are coming from china (generally) and your need 2-3 week to get them.

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