Open Source Hardware ESP32-POE board now has new version with 3000VDC galvanic insulation

ESP32-POE is one of our best selling boards, it’s low cost less than EUR 18 in single quantity and allow you to make IoT sensor network with existing Ethernet POE infrastructure.

The end node can provide up to 4W combined on +5V and +3.3V output to external components and circuits which is more than enough for most applications.

To simplify the design and lower the cost ESP32-POE has no galvanic insulation.

Some customers asked can we add such insulation – sure it’s possible, meet the new ESP32-POE-ISO. So here above on the picture you see first samples of the insulated POE board.

We wanted to keep is as similar to existing POE as possible, as you can see the new board is just 15 mm longer and keep same pinout on the connectors, allowing ESP32-POE to be directly replaced with ESP32-POE-ISO.

What are the benefits? Now you can safely debug your ESP32-POE-ISO while connected both to computer with USB cable and Ethernet POE cable.

For the insulation we use 2W DCDC converter with 3000VAC insulation. The available 400mA are split between ESP32 and external circuit and in most application will be sufficient.

The price of ESP32-POE-ISO is EUR 23.95 (only EUR 6 more than non-isolated ESP32-POE) in single quantity.

If 2W are not enough, we can produce same board with 3W DCDC which allow 600mA current, but the price will rise with another 3 EUR to EUR 26.95 in single quantity.

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.

 

 

C awesomeness (not)

Few days ago I was asked question what would be the output of this code:

#include <stdio.h>
int main()
{
      int a = 5;

      printf("%d %d %d %d\n",a++,a++,++a,a++);

      return 0;
}

Nothing special, right? But C standard do not specify how printf evaluates it’s parameters, so it’s left up to the C compiler and here the fun part starts.

Old C compilers would be a bit more predictable as they would start evaluating from the top of the stack to the bottom i.e. right to left, but the new ones heavy optimize and try to execute some instructions in parallel, so the only certain thing is that at the printf “;” point of synchronization “a” would be incremented 4 time, but nobody knows in what order.

Compiled with GCC/Code Blocks the output is:

Again nobody guarantee that if you re-compile on different computer /CPU the result will be same!

Even changing the code with one more line like enter the value of a with scanf leads to different result:

So good practice will be to avoid any calculations inside printf and to search logic there. Do these separately where compiler has to stick to C standard and rules.

 

How to use A20 CAN interface with the A20 universal Armbian image for OLinuXino

To use A20 CAN interface you need A20-OLinuXino board and A20-CAN board.

Then you have to install the armbian A20 CAN overlay:

• Download the dts file from:
  https://github.com/armbian/sunxi-DT-overlays/blob/master/sun7i-a20/sun7i-a20-can.dts
• Backup your SD card where the Linux image for OLinuXino is.
• Copy to the SD card the downloaded file.
• Insert the SD card into you A20-Olinuxino.
• Power on the board and after boot enter following command:

 

$ sudo armbian-add-overlay <path_to_the_dts_file>

 

• connect A20-CAN to your OLinuXino and reboot.

You can see if CAN is available now:

$ ifconfig -a

   can0     Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 
            NOARP MTU:16 Metric:1
            RX packets:0 errors:0 dropped:0 overruns:0 frame:0
            TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:10
            RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
            Interrupt:51

 

To use CAN interface you can install can-utils and setup the CAN interface:

$ sudo apt-get install can-utils 
$ ip link set can0 down
$ ip link set can0 type can bitrate 100000 triple-sampling on loopback off
$ ip link set can0 up

 

Now conect A20-CAN to the CAN network two wire interface.

To send a packet over CAN use :

cansend <can_interface> <packet>

 

For instance:

$ cansend can0 5AA#10.10.10

 

To sniff for CAN network messages you can use candump :

$ candump can0

 

Now you can log your car CAN networking messages and interpret them. There is plenty of info on the web about the different CAN messages which are exchanged on car CAN bus.

openSUSE leap 15 on the TERES-I

Torsten Duwe send us note that he is working on openSUSE Leap 15 image for TERES-I which is at same state like the Armbian image.

For these who are interested they can follow the progress here.

TERES-I Open Source Hardware Laptop has new experimental Armbian Mainline Linux image for download

We uploaded few days ago Armbian experimental mainline linux image for TERES-I on our ftp.

There are still few known issues which we work on, but we wanted to upload this experimental image so other people can start playing with.

What is new?

• eMMC now run x3 times faster which improves the overall user experience.
• OpenGL with LIMA

Known issues:

• Automatically turns on upon applying power via the PWR_JACK, we need time to patch mainline uboot
• No sleep or suspend, WIP.
• Bluetooth not working out-of-the-box – fixed in Olimex release if you install the package
  ftp://staging.olimex.com/Allwinner_Images/A64-Teres/linux/armbian_experimental/teres-bluetooth_0.2-1_arm64_armbian.deb
  with command:

  dpkg -i teres-bluetooth_0.2-1_arm64_armbian.deb

• Keyboard LEDs not working – fixed in Olimex release – install the package

  ftp://staging.olimex.com/Allwinner_Images/A64-Teres/linux/armbian_experimental/teres1-ledctrl_0.1-1_armbian_arm64.deb

  with command:

  dpkg -i teres1-ledctrl_0.1-1_armbian_arm64.deb

• The LCD brightness is low by default (20%) – fixed in Olimex release – to increase it type in the console

  echo 9 > /sys/class/backlight/backlight/brightness

• no video player acceleration, to be fixed in the next release planned for 22.02.2019

 

Bye Bye G+, Hello Mastodon (Fosstodon.org)

G+ is closing our account from April 2nd, we have no idea if they will keep our posts or will delete them, anyway there are always copies in Twitter and Facebook.

As many people do not want to use Twitter and Facebook for their own reasons, we searched for G+ replacement and it seems that Mastodon is the perfect choice.

So we are replacing now G+ with Mastodon and you can read our posts at https://fosstodon.org/@olimex