An open implementation for a SDI-12 Sensor node, based on Ultra-Low-Power Bluetooth CPU


  • Build your own SDI-12 V1.3 compatible Ultra-Low-Power Sensor with (often) less than 50 lines of Code
  • Use traditional SDI-I2 Bus or SDI12-Over-BLE to communicate with your Sensor
  • No APP required, use Standard WEB-Blueooth-API (Live demo: BLE API Live (in Repository LTX BLE Demo)
  • Optional: Secure Firmware-Updates-over-BLE (via BLE-API), Access Control via PIN, …
The core module of Open-SDI12-Blue

Read more:


Own PHP scripts on Mycloud NAS server (FW 5.18.117)

Only when I had already bought the small Mycloud NAS did I notice that it contains everything necessary (PHP, SQL, web server), but only allows the user a few ready-made apps. I was really very disappointed about it !!!
I only need a few small PHP scripts for everyday use. So what to do?

=> The fastest possible solution is to “inject” your own PHP into the WordPress APP 😉

WordPress offers the possibility of adding your own PHP snippets, there are various plugins for this, e.g. the “XYZ PHP Code” (from ‘’). A snippet is then used to simply copy a directory of the “accessible” NAS_DISC storage into a subdirectory of WordPress. Your own script is then under “NAS_HTTP://WordPress/ xxx/…”, but that’s no problem …

1.) Create a directory in which the freely accessible PHP scripts are located. In my case they are in “NAS_DISC://family/jo/fjp_php/”
e.g. “index.php”:

<!-- Source of this file: NAS:/family/jo/fjp_php/index.php -->
    <head><title>JO NAS</title></head>
    <?php echo "PHP-Time: ".time(); ?>

2.) Install the WordPress APP on the NAS (database user is localhost -> ‘root’ (no password required)).

3.) Install a PHP editor plugin in the WordPress Admin-Page.

4.) Create a snippet which then will copy the free NAS directory to “NAS_HTTP://WordPress/fjp”:

// flat copy NAS-Dir NAS://'family/jo/fjp_php' to 'NAS_IP://WordPress/fjp'
// Version 1.0: No Dir-Copy and No Remove of old files
foreach($sw as $df){
    if($file=='.'||$file=='..'||is_dir("$sdir/$df")) continue;
    echo "Copy '$df'<br>";
    file_put_contents("$tdir/$df", file_get_contents("$sdir/$df"));
echo "OK - <a href='$ldir' >Link:$ldir</a><br>";

5.) It is sufficient to run this plugin as a “preview”.

6.) Now “NAS_HTTP://WordPress/fjp” (index.php (or .html)) is ready.

Thats it

DS18B20 Fakes – The Good, the Bad and the Ugly

The original DS1820, DS18B20 and DS18S20 from Maxim-Integrated are well-known sensors and the accuracy and long term stability is really excellent (especially the “old” DS1820) is now on the market for >25 years. And I am using these parts for almost 25 years now 🙂

Recently I bought several “DS18B20” Temperature Sensors (waterproof in stainless steel caps and with cable) at *incredible low price* (ca. 1 EUR/pcs) and from different suppliers. This is much lower than the high volume price of raw DS18B20 parts from Maxim-Integrated directly.
I tested these sensors very carfully and found out, that obviously none of them was 100% identical to proofen genuine DS18B20 (or DS18S20). Oops…
My tests showed, that there were at least two different clones, counterfait or faked chips used:

  • The measured temperatures were OK for all (range 0°C..30°C, (+/- 0.5 °C)).
  • The mechanical quality (waterproof sealing, cables, stainless steel caps) was OK for all.
  • One lot was very close to the characteristics of genuine DS18B20, except the serial number was some kind of “unusual”. But everything else was Ok.
  • One lot obviously had different power up values in the “scratch pad” (an internal flash memory) and was (sometimes) instable with the protocol. Also, these sensors showed wrong values after power up (obviously in the range of the room temperature, but definitely not correct!). Very strange (and I named these “the Ugly”).

I found a very interesting site about this topic: . The author found even more than 4 types of different clones!

In any case: It seems (after long tests), that some of the clones are Ok for uncritical use (nevertheless I added intensive checks to my drivers to distinguish between the “The Good, the Bad and the Ugly”…).

LTraX_CC131x – T-2-Cloud Cool-Chain-Logger with Mobile Internet via 2G/3G/4G

This is the first Application-Note for the LTraX_CC131x! It is completely Open-Source, you can find all documentation, files, schematics, software, scripts here: in the LTrax Media Browser.

To the LTraX Demo Server…

And here is the demo server (completely written in PHP and also completely Open-Source)

The device is a cool-chain-datalogger that can run for up to 2-3 years (!) with 4 cheap Alkaline Batteries, if data are transmitted to the server only 2-4 times per day (of course in case of alarms it could start a tranmission immediatelly, because it measures every few minutes).

The device uses digital high precision sensors, so a large number of sensors can be connected to one LTraX. Because the LTraX comes with an embedded Filesystem, the software and function is clear and easy. Also the software and drivers have beend developed and tested very carefully! And not to forget: Always possible:  Secure Firmware Updates via Mobile Internet with the JesFs-Bootloader!

LTraX_CC131x T-2-Cloud – Cool-Chain-Logger with Mobile Internet

Worrying about the SIM? Forget it! Since a short time, Prepaid SIMs are available (August 2018):

  • for costs arround 10 EUR only (ca.) (!)
  • valid for 10 years or more (!)
  • valid in Europe or (almost) Worldwide
  • with included volumes of up to 500 MB

A selection of 10 EUR (ca.) Prepaid SIMs for M2M

So, don’t wait!

The LTraX_CC131x V1.0 Module (here with 2G modem assembled)

LTrax_CC131x – IoT with Firmware everywhere

The LTrax_CC131x is an Ultra-Low-Power Open-Source IoT Platform

Yes! It works!

  • Ultra-Low-Power: 3.6-14Volt, Sleeping (RTC running and I/O ports IRQ-armed): <5uA, active (CPU@48MHz): 1-15mA
  • CPU: up to 356kB Flash and up to 80.5kB RAM
  • Simple-Link Wireless CPU (CC1310 or CC1312)
  • Up to 16MB Serial Flash with JesFs-File System
  • Local Radio: 868/915 MHz
  • 2G/3G/LTE Modem on Board for Mobile Internet
  • Secure AES-Bootloader on the CPU allows Firmware Updates from everywhere (especially via Mobile Internet)
  • Open Source and compeletly designed in C (TI-RTOS)
  • With PHP libraries for the peered Webserver (Open Source)
  • Tested: >4000 Transmission (each ca. 1kb data and each with complete network in/out registration ) via 2G Mobile Internet with only 4 Alkaline 1.5V AA-Batteries. In other words: >10 years of daily data (if using low self-discharge batteries).

The LTrax logo

JesFs – Jo’s Embedded Serial Flash System V1.5

JesFs – Jo’s Embedded Serial File System

Definitely files will be on of the most important key topics in the upcoming IoT. Because files separate functionality and data.

Just think of very simple things like language data: on a “very small” Embedded Device (not something “big” like an Embedded Linux, but something that can run with small batteries for years): [More…]

QR_Vis V1.0 – QR Code Generator with C Interface

QR Code
This QR Code links to my page

Ever thought of using QR Codes? With QR Codes you can:

  • Generate Links
  • Access WiFi Networks
  • GPS Coordinates

Using some free libs, I wrote this this little tool. It is also very useful to generate C arrays for bitmaps (E.g. for use on embedded displays). Included is the complete C sourcode (C++ (for RAD Studio) and Exe for Windows). Feel free to use it as you want. This is free software. No warranty!

Download:  [QR_VIS V1.0 (as ZIP)]