LoRa experiments in Plovdiv

We are working for some months on OSHW LoRa nodes and our goal is to bring up free to use for non for profit Smart City solutions LoRaWAN network which to cover city of Plovdiv .

Yesterday we installed our First LoRaWAN Gateway made with T2-OLinuXino-LIME2-e16GBs16MB + RK831 + +6dBi rod antenna on Rilon Building which is about in the city center and with height good for antenna installation.

You can see on above map – the “Raspberry Pi” is hardcoded in RK831 firmware but do not worry there is industrial grade Linux computer in the gateway.

 

We start experimenting with our LoRa868 and MOD-LoRa868 modules and made portable GPS tracker device like this:

The results are nice. We cover almost 2km circle around the antenna. With few spots which are shadowed by tall building.

The secret in the big distance is the good gain gateway antenna!

We really are impatient to release these LoRa gadgets as soon as possible, but unfortunately it takes much more time than we expected.

There were lot of issues with the Semtech/ARMmbed reference designs like the RF part of their 868Mhz design actually has components values which make 915Mhz device and vice versa. We spent weeks to understand why the communication distance is not as good as expected, before we realize that we use 915Mhz LoRa nodes with 868Mhz antennas! Once we get everything complete and tested will put our boards on the web for sale and publish OSHW their correct schematics and component values, so other will not waste their time like we did.

One issue we encountered with RK831 Gateway is that it freeze from time to time when receive malformed packets and need to restart. As RK831 firmware is not open source we can’t debug the cause of this problem. The workaround now is when host lose connection with gateway just reboot latter. Really not most elegant solution, but so far we can’t do anything else.

We are preparing two more Gateways to install in the next days, which will cover more parts of the city.

 

 

FOSDEM slides and video

FOSDEM is always impressive, even for people like me who go there for 7th time. It’s great place where you can see developers for almost every FOSS big project and talk face to face.

It’s really pleasure to see that last years there is Hardware related dev rooms too.

KiCad as always attracted lot of attention

but CAD and OSHW devroom was pretty small, so people are waiting on long tails to get in and just few lucky ones succeed:

For security reason the organizers didn’t allow people to stay standing or sitting on the floor, but this didn’t stop all. Next day I spoke to lot of friends and they said – I knew there will be no space for all who want to enter, so I just stay at the cafeteria and watched the stream.

It was same situation at the Andre Przywara talk One image to rule them all. There was no space in the room to accommodate all people who wanted to attend it.

There were three talks from Plovdiv at FOSDEM this year 🙂 Our friend Leon Anavi had two talks Making Open Source Hardware for Retrogaming on Raspberry Pi and The Software Developer’s Guide to Open Source Hardware. It’s cool as his full time job is as software engineer but as you can see he does OSHW in his free time and obviously like to talk more about his hobby than his daily work 🙂

I talked about some new OSHW boards we are working on last few months.

The idea is to build LoRaWAN infrastructire and install some free Smart City solutions in Plovdiv which to set example and to put all our work on GitHub so if other cities want to follow to be able to replicate and scale what we did and hopefully people to get aware more about the power of the open source hardware and software solutions.

Here are my slides and here is my attempt to speak English at FOSDEM. Sorry subtitles are not available 🙂

It was incredible pleasant surprise to see OLinuXino-LIME2 mentioned in Danny Haidar‘s lighting talk Creating a Computing Revolution: from Personal Computers to Personal Servers.

FOSDEM 2019 is this weekend in Bruxelles

FOSDEM the biggest FOSS/OSHW event in Europe is this weekend in Universite Libre de Bruxelles

FOSDEM traditionally starts Friday evening in Delirium Cafe.

With 47 devrooms, 7 main tracks, Keynotes and Lighting talks everyone can find group with his interest.

Olimex will present our new IoT developments with KiCAD at CAD and Open hardware devroom in Sunday.

If you want to meet and talk please send email to info@olimex.com, we will be in Delirium Cafe this evening and at ULB in the weekend.

Working with A20 OLinuXino or SOM GPIOs when using new Armbian based A20 universal Linux image

A20 GPIO ports are 32 bit registers listed in alphabetical order PA, PB, PC, PD, PE, PF, PG, PH, PI.

In Armbian GPIO ports are numbered from 0 to 287 corresponding from PA0 to PI31.

The GPIO number is calculating using this formula:

gpioNumber = (Port Letter - 'A') * 32 + pinNumber

 

For instance GREEN STATUS LED on A20-OLinuXino-LIME2 is connected to port PH2. This will correspond to GPIO number:

('H'-'A' = 7) * 32 + 2 = 226

 

All GPIO operations in shell should be made as super user. First we have to register the gpio in the Linux Kernel with this command:

sudo echo 226 > /sys/class/gpio/export

 

to check if we did registered this gpio successfully we use ls command:

sudo ls /sys/class/gpio

 

If you did everything correctly you will see gpio226 listed.

Then you have to specify what will be this GPIO input or output. This is done with writing “in” or “out” in gpioxx direction directory. In this case we want to drive the STATUS LED so we have to make it output:

sudo echo out > /sys/class/gpio/gpio226/direction

 

Once we set the GPIO as output we can write 1 or 0 to it’s value and this will make GPIO port to supply 3.3V when 1 is written or 0V when 0 is written.

To switch the LED on we have to write 1:

sudo echo 1 > /sys/class/gpio/gpio226/value

 

Yay the green LED is now lighting. If we want to switch it off we have to write 0:

sudo echo 0 > /sys/class/gpio/gpio226/value

 

To read the GPIO state it has to be set as input first with the command:

sudo echo in > /sys/class/gpio/gpioXXX/direction

 

where XXX is GPIO port number calculated as described above. Then to read the GPIO state you use this command:

sudo cat /sys/class/gpio/gpioXXX/value

the result will be 0 if the GPIO voltage is between 0.0-1.0V and 1 if the voltage is between 2.3-3.3V. If the voltage on the GPIO is between 1.0 and 2.3V the attempt to read will return randomly value 0 or 1.

Be careful when playing with the GPIO ports, some of them are wired to important peripherials like LCD, Ethernet, USB, SATA etc and writing bad values may break the functionality or even damage the board. Test your knowledge on GPIOs which are not connected to anything is best approach.

We are prepare now new version of PyA20 Python module which will add access to GPIO, SPI, I2C, Serial resources of A20 directly from Python code to work with the new universal A20 Armbian Linux image.

EDIT 2019-01-25 14:24:

We got question how fast is the access to the GPIOs via shell. Sure it’s not fast and made just for slow processes like switching on and off relays, or polling status of buttons or sensors which do not change often their state. Running this code below:

nano toggle_led_lime2.sh

 

Enter inside the file this code:

#!/bin/bash
# the lime2 led is PH2 - 32*(8-1) + 2 = 226

echo 226 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio226/direction
while [ 1 -eq 1 ]
do
echo 1 > /sys/class/gpio/gpio226/value
echo 0 > /sys/class/gpio/gpio226/value
done

 

Save and exit, then make executable and run

chmod +x toggle_led_lime2.sh
./toggle_led_lime2.sh

 

We can see square wave with oscilloscope on PH2 with frequency between 3 and 4 kHz. i.e. pulses with high state 125-150uS and low state 125-150uS.

Shell is slow, if we write same code in C:

#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>

#define PH2        226    // (32 * 7) + 2
#define GPIO_PATH  "/sys/class/gpio/gpio226/value"

int main() {
    int ret;
    int fd;

    fd = open(GPIO_PATH, O_RDWR);
    if (fd < 0)
        return errno;

    while(1) {
        ret = write(fd, "1", 1);
        ret = write(fd, "0", 1);
    }

    return 0;
}

 

The new code produces square wave with 2.13 us high and low state i.e. approx 235 kHz or about 50 times faster than access via shell.

We just uploaded on Youtube video for eduArdu features and how to install and use the Arduino examples from GitHub

First Steps with eduArdu workshop on 15th of December!

On December 15th together with our friends from TuxCon we will make workshop with our new educational board eduArdu in Olimex training building.

If you want to be part of this even come and join us, the event is free to participate.

We will show you how to use all eduArdu features with Arduino and Snap.

Be prepared to play games with fruits and people-touch, to make animations with LED matrix, to generate music, detect intruders with the PIR sensors, to switch on and off air conditioners and even create music instruments!

Educators may apply for free board which to receive at this event.

 

eduArdu is new Open Source Hardware educational board targeting kid’s digital education

Few weeks ago we got contacted by Digital Kidz an non for profit foundation which goals are to support digital literacy and innovative education in the schools. They needed hardware board, which to be easy to use and to allow entry level programming with Scratch and Arduino for beginners. They were ready to pay for the development, but we liked the idea and decided to design one such board for free and release it as Open Source Hardware.

The result is here:

The design is based on ATmega32U4 which is easily programmable with Arduino IDE. We named it “eduArdu” as this is educational board programmable with Arduino.

eduArdu has these features:

• USB connector for programming and power supply
• red LED matrix 8×8 which allow text and small image animations
• X-Y Joystick with push button for navigation
• Microphone for Audio sensing and interactions
• Speaker for Audio output
• Light sensor with LDR
• Digital temperature sensor
• RGB LED
• Status LED
• IR remote control LED and receiver to talk to other boards, TVs, Air conditioners, etc.
• PIR motion detector up to 6 meter range
• UltraSound distance measurement sensor
• Two SERVO motor connectors (to build easily two wheel robot car)
• LiPo charger so the whole board may work on LiPO power
• 6 Makey-Makey style buttons
• UEXT connector for additional modules

The board is shaped like Game console. The first prototypes will be ready in 2 weeks.

Target sale price is EUR 15.00