Welcome to a new Voltlog, this will be a rather short video where I will be talking about a rather common subject, LEDs. I’m sure everyone uses them in their projects but if you are like me you probably never cared about the efficiency of the LEDs you use for signaling the status of something on your microcontroller board. So what I was doing most of the time was picking the least expensive LED available while still picking a known manufacturer like Kingbright or Lite-on or Osram just to avoid quality issues. And that was my voltage rail indicator LED or my blinky LED for signaling some status. But this ofcourse meant I needed to drive those LEDs with a fairly high current of 15-20mA to get decent brightness out of them and that might be OK for numerous applications but in this video i want to talk about high efficiency LEDs and how your project could be nicer because of them.
Tag: voltlog
ESP32 Aquarium Terrarium Controller – Voltlog #361
This project started when a friend of mine which has a snake terrarium asked for my help to build a system that is capable of regulating temperature and humidity so the snake can live in optimum conditions. I’m not necessarily a snake lover, I would rather stay away from these kinds of creatures but that doesn’t stop me from helping my friend.
I started by figuring out what he uses to control temperature and humidity and it turns out there is some sort of a lamp to provide heat from above, some sort of mains powered stone that heats up and a water fountain, probably one that runs with fog to control the humidity. All of these are mains powered and only need simple on/off control which makes things simple when designing the electronics board.
In terms of digital control I figured it would be nice to have to be able to update the set points and check on the status values wirelessly so I went with an ESP32 modules. This also helps to add an extra layer of protection to keep the user away from the dangerous mains voltages present on the relays. I can have the whole board, enclosed in a plastic box so the user never goes near the mains voltages.
InTheMail | Voltlog #360
Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time. For this video we have a wide selection of items and we’re gonna start with this jewelers magnifying glass, I’ve had one of these for years and it’s been great for reading small numbers of chips but recently I found myself needing more than one between the home lab and the office so I got a second one. Here is an example of how I would use this to read some very small numbers. Of Course I have the microscope but I usually keep that unplugged and covered to protect from dust so for reading a chip number it’s just easier to use one of these. Same as always if you are interested in getting one, you will find links in the description below the video.
Silabs CP2104 No Activity on RX TX LEDs Bug – Voltlog #359
In Voltlog #357 I talked about a bug affecting the programming of ESP32 modules via Serial Bootloader, basically the issue was caused by an incorrect reset sequence regarding the EN and IO0 signals and I also showed a fix which involved adding a capacitor to delay the EN line.
Well, this week I’m gonna show you another bug which I encountered recently but this time with the CP2104 USB to serial converter chip from Silabs. So recently I designed this little board called VoltLink, it’s basically a usb to serial converter board but one that also integrates the auto-reset circuitry needed for programming Espressif modules like the ESP8266 & ESP32. I also have a 1mm pitch JST-SH connector with a standard pinout that I use in all of my designs and this helps with space savings on small circuit boards.
Well after assembling one of these boards, I connected it to my computer, the new virtual serial port was created and I thought everything was running fine, except it wasn’t. I quickly discovered that the status LEDs were not reacting when there was communication on the serial lines. I don’t know about you but I want my status LEDs to be functional, it helps me get a quick visual understanding of the communication happening on the serial lines. I don’t need anything specific, I just need to know that there is activity and if there is a lot of activity or less activity.
UNI-T UTi260B Best Thermal Camera For The Money? – Voltlog #358
Welcome to a new Voltlog, in this video we’re going to be taking a look at the UNI-T UTI260B professional thermal camera. As you may know I used to own a FLIR ONE iOS thermal camera that I was using with my phone, it was working okay, it had a thermal resolution of x and a picture resolution of because it had the two cameras and it was doing the overlay thing. Well one day I dropped that camera which caused a fault in the lightning connector and unfortunately FLIR does not sell replacements.
So I started searching for a new camera, I was thinking of getting another FLIR one but then I discovered this UNI-T camera which I believe is a fairly new model and not a lot of people know about it. But let me tell you the specs, thermal camera resolution 256*192px, visible spectrum resolution 640x480px it can mix the two images similar to how FLIR does it, 2.8” TFT LCD, 5000mAh battery which gives a battery life o at least 6hours, temperature range -15C-550C, rugged design with IP65 protection, micro-sd card for data storage, up to 4 points of temperature measurement. This is a massive upgrade for me, over the FLIR ONE I used to have.
A fatal error occurred: Failed to connect to ESP32 – Voltlog #357
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header. This is an error on which I have spent long hours trying to figure out what’s causing it and how to fix it. If you are struggling with the same error on Windows, stick with me, I’ll show you how to fix it.
For example in my case, the issue manifests itself on a single windows computer out of 4 tested and it doesn’t really matter at which baud rate I’m trying to upload it can be 115K or 900K, it doesn’t matter if you are using Arduino IDE or PlatformIO, I still get the error because it’s not caused by the IDE. And also I’ve experienced this with both FTDI and Silabs chips. Sometimes the behavior can be random, meaning it might work 1 out of 10 tries which can get really frustrating, especially if it happens in the most inappropriate times as these problems tend to happen.
First I tried understanding the issue, this is clearly a problem with how the ESP32 resets, it doesn’t go into the correct bootloader mode for code upload. By looking at this repository which is managed by Espressif we get some info on the expected sequence, and we learn that the ESP32 should have GPIO0 pulled low during reset for it to go into serial bootloader mode. Reset is triggered by pulling the EN or Reset pin low. They don’t give us a clear timing diagram of what this should look like but I’m going to assume the state of GPIO0 is read while EN signal goes back high to release it from reset. So the logic thing was to put a scope on these signals and check it out.
VoltLink™ A Fancy USB Serial Adapter (ESP32 Programmer) – Voltlog #356
Welcome to a new Voltlog, today I’ll be showing you how I created my own usb to serial adapter board and we’ll go through some of the design decisions I had to make and I will explain the reasoning behind making these choices but first let me tell you the background of the story, Personally I’ve always liked having my own usb to serial adapter and here is one that I designed something like 10 years ago maybe more. The layout is not great, my PCB skills were obviously not as good as they are today but nonetheless, I created this adapter as an exercise but also for the important purpose of having a reliable and flexible tool. Reliable because I could control the chip that I’m using. It was a Silabs CP2103 and I was getting it from a well known distributor.
Flexible because I had all the IOs of the chip broen out to 0.1 inch headers which could mean that I had the option to trigger a reset on a particular board or something along those lines. And I’ve also designed other adapters based on FTDI chips and more recently based on the CH340 family of chinese chips.
So this brings me to today’s project, I designed this new adapter for two reasons: one is the good old reason of reliability, you can’t trust the adapters you’re getting from aliexpress, they’re almost always using fake chips and generally are of lower build quality. I want a reliable CP2104 series chip in here, I want it to be able to sustain high bit rates for fast uploading of firmware images to target boards.
Testing The Xiaomi 100W Type-C Car Charger – Voltlog #355
In a previous mailbag video I showed this Xiaomi dual USB port car charger which is capable of power delivery over USB Type-C. Xiaomi claims this is capable of up to 20V 5A output on the USB Type-C port. In the mailbag video I wasn’t able to test these claimed specs but today I have prepared a test setup so we can take a closer look at these specs.
In terms of specs I had a better look at the small user manual that comes with the product, it’s all in chinese so I had to use google translate on these but the unit takes 12 to 24V DC input. It’s unclear to me if you can use this in a 24V car system because you would be operating right at the upper limit of the input and the manual isn’t clear on that aspect.
You got two outputs, USB-A port capable of quick charge protocol 5V at 3A or 9V at 2A And a second USB type-C output which supports power delivery protocol up to 20V and 5A max. If you’re using both ports at the same time the maximum combined total power output is 68W.
InTheMail | Voltlog #354
Welcome to a new InTheMail, the series that will touch both your passion for electronics and your bank account at the same time. We’re gonna start this video with an item I do not recommend buying, this is a power meter that has been sitting in my mailbag basket for over a year now if not more and these past few days I powered it on for the first time, I realized it’s not very useful, because the accuracy is pretty bad. It does claim to measure up to 140A which would probably make it okay for some high current measurements and that was the original reason I got this to measure to brushless motor power consumption at various loads but if we’re talking about currents below 5A the accuracy is pretty crappy so I wouldn’t recommend you get something like this.
Reverse Battery Protection With Mosfet (no voltage drop) – Voltlog #353
Welcome to a new Voltlog, today we’re going to be talking about reverse battery protection, I’m gonna be showing you a few methods for achieving this protection but I’m going to be focusing specifically on low power designs, where you might be using let’s say a single coin cell battery.
When we’re talking about higher input voltages, battery protection is pretty simple, you can simply add an inline Schottky diode, if the input voltage is reversed, the diode will be reversed biased and it will block the current flow. There is about 0.5V voltage drop on your diode but if you have a 9V input into a 5V regulator, there’s plenty of margin to afford losing half a volt. There is also the power dissipation to consider in that case, so you multiply the current with the voltage drop and you get your power dissipation into the diode, you pick an appropriate diode capable of dissipating that and the problem is solved.
Now when you start talking about low power devices, specifically those powered by coin cells, it gets a little tricky to get some reverse polarity protection into your circuit. Because our battery voltage is now just 3V we can’t afford losing 0.5V on our input diode, that will ruin our battery life, it will waste the little precious energy we have stored in the coin cell and might prevent our circuit from powering up.