Hardware

A small note on my experiences so far. I have settled on using this screen for most cases where I wanted to use a bigger screen for output. Creating small UX-es is awesome. What is also great is that I turn the backlight off after a little while, and then a touch turns it back on again. Similarly, using a touch to turn the screen on and off is nice for when you don't want the screen to shine it's light into the room all the time. I have also gotten it to work slightly faster by creating a better way of handling the serial data it sends. I've also learned that you can send longer strings to it all at once. You need to send the length of the string in the command. I haven't implemented this in my own code yet, but I recently learned about it by better reading the documentation. Something more worrying is that two of the six screens have stopped working. The screens turn on, but there is no serial communication. I believe this is caused by how I handled the screens, and creating small shorts on the back of the screen. My recommendation is to add some non-conductive tape to the entire back to avoid this. Make sure your other electronics don't accidentally touch its back. The resistive touch screen works well, but if there was a capacitive version of the screen I would probably switch to that. Finally, the screen can be separated from the PCB below. It's just attached with double sided tape.

I have a question. On the convection fan motor is the fan (pictured) for convection or is there another fan inclosed and the one pictured for cooling the motor? I like this build and plan on doing one.

You can power the Nano with 3 x AA (or AAA) alkaline cells (4.5v) connected to the 5v pin. The 4.5v will also be suitable Speed Test Scrabble Word Finder Solitaire for powering a servo. And the AA (or AAA) cells will last longer than the 9v PP3 style battery.

your can use JEDEC solderprofile as guidance, as Pb-free (Leadfree) is standard nowadays and the max temperature is 260°C, which can be seen in below solder profile. and don't heat it too long... https://www.cypress.com/file/41231/download

@scalz @skywatch Thanks both for thoughts, but managed to solve the original problem when I stumbled across why the JSN-SR04-2.0 would not work at 3.3v. The standard pulse of 10 microseconds changed to 15 had it working perfectly rather than intermittently. All that pain over two years for the sake of 5 microseconds.:stuck_out_tongue_winking_eye: Will try playing with a high psrr LDO post booster for potential future needs, as the interaction completely threw me. The error only showed up when the ultrasonic range extended (tank emptied), blissfully unaware until then. I don't have the skills to design a booster, and components on the commercial ones are difficult if not impossible to identify, so post treatment it will have to be.

I emailed Hi-Link about the HLK-PW01 power supplies that @rmh, @yannik-mündler and myself purchased. These are the power supplies with a removable bottom. I sent the following email to Sunny at Hi-Link (contact info: http://www.hlktech.net/contact.php). ++++ Hello, Are the two HLK-PM01s in the attached images genuine Hi-Link parts? A major difference is the part on the right has a bottom cover that is easily removable. I bought the part on the left from an Aliexpress seller in July 2018. The part on the right was bought from the same Aliexpress seller in May 2019. Thank you very much for your help. ++++ Here is Sunny's reply: ++++ Now all of our module are use new version . The one you bought on 2019 is the new version, the old version is not used yet. By the way,May I know you are the final user or the reseller? If you are worried about it,you can buy from our website www.hlktech.net or our Aliexpress store https://hlktech.aliexpress.com/store/211069 directly. ++++ I went to the Aliexpress page in their email and found the HLK-PM01 page. On that page they say: ++++ Recently,there are many fake module in the market,in order to Standardize the market environment,keep benifit for the customers,We,Hi-Link,changed our module to the new but more quality version,the back of new version is show as the following picture,currently,the old version and new version were sent random,please pay attention to that!thank you very much! ++++ They also show images of the previous version (which we are all familiar with) and the new version (with the removable bottom). So, it appears the HLK-PW01 power supplies with the removable bottom, from a reliable vendor, or directly from Hi-Link, are genuine Hi-Link power supplies. Below is my two images of the bottom of the two genuine power supplies (old on the left, new on the right). [image: 1560350467101-img_20190607_164006-resized.jpg] [image: 1560350493263-img_20190607_164018-resized.jpg]

Welcome to the MySensors forum. MySensors is a library you can use to create a wireless mesh network of sensors which communicate with a central point, such as your Raspberry Pi. You could attach an Arduino Nano to USB and talk to it via Serial. You could create a MySensors network, which you could also communicate to via an arduino+radio on your USB port. Then you could attach countless sensors. There is a ready-to-go sketch for the MH-Z19B.

Hi @Siddharth-Velappan The warmup time of the MH Z19b is 3 minutes. So 2 is probably fine, but you could probably do 3 just in case. Although 2 would save your more battery time. Do you mind explaining your setup a bit more? I would love to do something similar but I do not know where to get started with the PIC microcontroller!

I use a similar board like this (though without the battery) to show the weather forecast for today and traffic information for upcoming routes in our walk-in closet. So I don't have to check the forecast on my phone while dressing.

guess no odb port?

RF performance depends a lot on what's the setup antenna shape (coiled/meandered less efficient, or straigth one), orientation, radiation shape, size, tuning (inside final enclosure might be different, good to check rssis and adjust if needed), quality (lot of bad/untuned on some ebay/Ali shops) GND plane size, software settings the test environment etc for example, here I use 868mhz. I have a compact outdoor RFM69CW node with a simple homemade coiled "wire" antenna (RFM69CW has lower TX power, no power amplifier) sending well at 45-50m from the house, and the RFM69HCW gateway (with power amplifier) is indoor. One thick wall and some trees. Elevation of both ends/antennas is 1.5m, default software settings (for bitrate etc). But in direct line of sight, outdoor, there are also people reporting up to 1-2km range. Compared to MySensors on 2.4ghz, it can be easier to get reliable indoor link with subghz. Like in case you would already have others protocols on 2.4, with wifi and expanders, zigbee, ble, mysensors is not yet resilient to interferences and overlapping freq with these others protocols.. (no frequency hopping for example). It means, 2.4ghz needs more care, and depends on long term evolution of your network..

@bjacobse Granted that is what he has, but it's a lot more effort reducing a Nano to pro-mini compared to the cost of a getting a pro-mini to begin surgery to start with... We all have devices bought with good intention gathering dust as we learn.... ;) One of these days will get a Nano to play with, but had dismissed it for battery applications from the start of this adventure and have seen no reason to reconsider that conclusion since.. For testbed or PSU applications, fine, but for battery applications?... As the Limerick man advised the driver seeking directions to Dublin, " I wouldn't start from here" :)

@arden you can found on this blog some sensors using NRF24L01 and Attiny84 http://domotique-diy.over-blog.com I think migrate mysensors to this project

@rpunkt if 3ma is your current draw while sleeping, you will quickly drain any battery or supercap. The "mini boost buck dc board" itself has a no-load current of 1.77mA. Might look here for low-power libraries and design considerations: http://www.home-automation-community.com/arduino-low-power-how-to-run-atmega328p-for-a-year-on-coin-cell-battery/ https://github.com/rocketscream/Low-Power

great work @arden, thanks for reporting back!

@arden nice work! Gateway can be on the same pi as the controller. Many people use that configuration. Personally I use Domoticz, because it is very easy to get started with. I think Hass has more features, so in the long run Hass might be a better choice.

Basically you have 2 options: You are present to watch when the port goes down something expensive like this: https://duckduckgo.com/?q=Safety+Light+Curtains&t=canonical&iar=images&iax=images&ia=images