News items for tag electronics - Koos van den Hout

2022-07-07 First signals on the logic analyzer circuit
The logic analyzer circuit I ordered came in today with the test leads. Both the circuit and the test leads have pins so I need something to connect those two. So the crate with PC cables was ransacked and a floppy drive cable is now connecting the logic analyzer and the test leads.

The logic analyzer shows up in linux as usb device:
Bus 002 Device 008: ID 1d50:608c OpenMoko, Inc. Fx2lafw
Finding software was quite easy: pulseview indeed works out of the box, complete with support for this logic analyzer.

I had a look around for something to analyze and finally settled on the ESP32 based NTP clock because that's still on a breadboard and signals are available. I can see the bits flowing between the ESP32 microcontroller and the display module.

I'm still seeing some bits come in on unconnected testleads so I'm not sure I am doing everything right. But it's a start!

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2022-06-08 My interests in electronics and security together: trying some hardware hacking
One of the subject areas I'm interested in at work is hardware security and hardware hacking. After doing things with rfid earlier I'm now looking at low-level electric interfaces. With the earlier hardware challenges in CTF contests in HackTheBox Cyber Apocalypse CTF 2022 - Intergalactic Chase and The HackTheBox & CryptoHack Cyber Apocalypse 2021 I got interested in logic analyzers. Those sounded expensive (but I never actually checked).

And then I read this bit: I recently got this 8ch cheap USB-C logic analyzer from AliExpress and the price shown is 5.42 US dollar. That's really cheap!

For that price I can buy one and not be too dissapointed when it blows up or fails to give me the joy I hope. So, ordered: one 8 channel logic analyzer and a set of test leads so I can actually clip this to a circuit. The price for me for the logic analyzer circuit is EUR 6.78 including delivery and taxes.

For software I learned about PulseView.

This hardware has limitations, but for simple decoding of hardware protocols this is a nice start.

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2022-04-01 Mention of my igate
In 2020 I built an igate: a device for receiving status packets on amateur frequencies and got it succesfully receiving packets and publishing them to the APRS network.

Since then the hardware has been in a corner of the radio shack receiving packets, building a good coverage of received packets and doing fine.

Today I noticed in Razzies April 2022 a Dutch-language electronic magazine of the Radio Amateurs Zoetermeer a nice mention of 'my' igate:
De enige gateway die dapper stand houdt is PE4KH-10: nota bene een iGate naar ontwerp van onze club: een RAZ iGate...
or translated: the only gateway still standing strong is PE4KH-10: notably an igate made to the design from our club: a RAZ igate.

It's nice to get this mention! The hardware is in the corner of the shack just doing its job and nothing else.

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2021-05-03 Refreshing rechargeable batteries
With lots of devices running on rechargeable batteries including toys with motors and lights we have accumulated quite a number of rechargeable batteries in our house. Some of them have been around for ages and others are more recent.

With the amount of batteries varying per device (we have seen 1,2,3,4 and 6 batteries per device) it's good to charge each battery individually as they may have different residual charges and always charging them in pairs when one is not as good will only make the difference worse.

But the charger for individual AA/AAA cells we have also wants to charge the batteries quite fast and will abort as soon as one cell doesn't accept the charge. More and more batteries got rejected this way, even relatively new ones.

The solution: a smart charger that has adjustable load current, can refresh a battery that has problems accepting charge and measures the charge in the battery. And does this for 4 batteries at the same time. I gathered batteries from all kinds of places (quite a collection) and started charging and measuring all of them. A number of batteries got rejected because even a "refresh charge" ended at less than 50% of the original capacity. Those batteries will be handled as chemical waste. The others with enough capacity left are now all in the big box of charged batteries. Most of them will not keep their charge until the moment we actually need them, but it's good to know they are usable.

I bought the https://www.conrad.nl/p/voltcraft-ipc-3-batterijlader-li-ion-nicd-nimh-10440-14500-16340-16650-17355-17500-17670-18490-18500-18650-1403321 from Conrad which has only one downside: the fan is somewhat noisy.

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2021-04-07 The NTP ham clock is ticking
esp32 based NTP ham clock on breadboard Recently the parts for the NTP ham clock I saw in the Electron magazine arrived: an ESP32 module and a TFT display. It took a bit before I had time to actually do something with them but recently I put the modules on breadboard and started making the needed connections. There are not a lot of those, only 8 wires need to be connected between the ESP32 microcontroller and the TFT display.

After some fiddling it worked and I managed to program it all with the settings I like, such as the right timezone rules for the Netherlands, 24 hour display on both clocks and it fetches the NTP time from the NTP server in the shed so it doesn't rely on outside connectivity.

Now to find a case for it and wire it neatly.

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2021-02-27 Ordered parts for an NTP ham clock
Today the Electron magazine of the Veron amateur radio club came in, the March 2021 Veron Electron (Dutch).

As I was browsing the magazine and reading articles I came across an article about building an NTP ham clock, consisting of an ESP32 module and a TFT LCD display, and the rest is all in software.

I directly wanted to build this, as this combines two of my interests: amateur radio and NTP time synchronization. It displays both the local time and the UTC time on the TFT display, just like PyHamClock does on my screen.

The article is based on the same project at W8BH projects which gives me a good descriptive pdf.

So I ordered an ESP32 module and ILI9341 TFT LCD display from an aliexpress seller and now I wait, because this will take about a month.

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2021-01-05 Sharing my christmas light code
I forked the github repository GitHub - jgarff/rpi_ws281x: Userspace Raspberry Pi PWM library for WS281X LEDs into my own GitHub - KHoos/rpi_ws281x: Userspace Raspberry Pi PWM library for WS281X LEDs and committed my code for using the 120 led ledstrip as christmas tree lights including morse code.

It's my first actual python code.

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2020-12-31 The igate is still receiving packets and slowly building coverage
Coverage map of PE4KH-10 igate around Utrecht Since the igate build was finished and the first packets were received I left it running. I did switch to a 5 volt power supply: it works fine on a USB charger powering the whole circuit board via the USB connector for the ESP32.

Packets are received from a large area around the city as shown. I'm glad it is all working and I hope to improve the APRS network coverage here locally a bit.

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2020-12-23 A bluetooth speaker that is also a serial port
I acquired a Blaupunkt BLP6100 Bluetooth speaker. Which turns out to support the following services via bluetooth:
  • Headset (audio for phone calls)
  • Handsfree operation (use buttons to accept, hangup or reject calls)
  • Audio sink (the main function of a bluetooth speaker)
  • Serial port
That last one I did not expect. I have tried opening the port with minicom and it will say carrier detect but sofar trying to wake it at 115200 or 9600 hasn't resulted in anything.

As a linux audio device it works fine. Or as a bluetooth speaker for my phone so I can listen to podcasts while walking around at home.

But the serial port makes me wonder!

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2020-12-05 Playing with a fully programmable LED strip
At work there is a sort-of competition for the best christmas decorations in the office. At the end of last year I considered doing something with programmable LEDs to 'participate' in this competition in 2020.

This year turned out somewhat different, but slowly my son is also somewhat interested in electronics, soldering and making the computer do something.

So I set out to find fully programmable LED strips. I found a good comparison of LED strips in a Youtube video: LED Strips, what's the difference? WS2811, WS2812B, 2812Eco, WS2813, WS2815, SK6812, SK9822. which compares the several available types and their pros and cons. After viewing this video and for my limited experiment I thought the WS2812B based LED strip would be the best choice. The next hurdle was controlling it and I found Connect and Control WS2812 RGB LED Strips via Raspberry Pi which has pointers to the right code.

I am not following the advice on that page about working with mains power cables. That looks dangerous.

I ordered a WS2812B based LED strip and a matching power supply for 5V 40Watt from a Dutch webshop and got it in a few days later. I was amused by the warning the webshop gave that a LED strip like this is for advanced users only because you have to add a controlling device and do all the programming. That is exactly what I intended to do!

Programming is in Python3, and I haven't written any Python code before. But with a lot of google searches and looking at samples I got the idea right.

I now have the LED strip blinking in exactly the patterns I want, including a nice pattern for a christmas tree. And it blinks 'MERRY CHRISTMAS' in morse code, because why not!

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