In a previous post I’ve been presented an idea for creating a kind of satellite solution for watching over pandemic progress over the world using low cost connected thermometers. You can get the details of this idea in my blog post “What IoT can propose against Pandemic“. Basically the proposal is to add an ultra low cost IoT communication feature into a thermometer and report the information when an over heat has been detected. That way we could be able to determine the level of pandemic and its geographical progression over time. So I won’t detail all the business model and financing proposal, you will find all of this in my previous post.
The second step is now to make a prototype of a such device to show how too make it possible. For making this I’ve selected the thermometer you see on the picture above and decided to hack it and connect it to Sigfox network. This thermometer comes from Amazon and cost 14€ but is really like all low cost thermometer we can find.
Remote Selfie shutter are really low cost Bluetooth 3 buttons that are really easy to hack for making different applications.
These button can be found on ebay, amazon or aliexpress like following this link for less that 6$. The button is paired to the smartphone and then allow to execute photo shoot without the need of any third party application.
The Sigfox keyapp is a useful tool you can buy or you can get when reaching the Sigfox kick-start session. Basically, this tool send a message each time you click on the button. This allow to check the network availability where you want just clicking on the button. Easy, useful !
The KeyApp have an internal battery, one led, one button. It is refill with the usb connector and it is based on TD1208. The internal firmware is a partial modem ; it can be used as a modem on serial port from a PC but not all the AT command are implemented on it.
My purpose was to modify this tool to send automatically message every 12 minutes. The firmware can be modified and upload on the standard way (take a look to my other posts). For sure by doing a such thing you take the risk of loosing warranty and you do it at your own risk.
To make it works you just have to know some of the cabling.
The Led is active HIGH and located on USR4 signal.
To enable the battery power, you must activate USR1 LOW
To read the button you must take a look on USR0
The battery is by default not powering the system until you switch USR1 to LOW. If you do not do this, the system will only work on the usb power. It means you can switch off the system simply by switching USR1 to high.
The last step to use a ATMega328P / Yabbas from the Arduino IDE is to plug it with a FTDI cable (TTL RS232 over USB). Personnally, I’m using the TTL-232R-3V3 to do it. The first step was to create an adaptor to transform this cable output to the YABBAS pinout.
I recently created a printed circuit board for a raspberry PI design i’m working on. By the past, when I did such things, the cost to make it was not accessible for a home made design. In 10 years things have change a lot and now, you can do it for less than 100€ for a 10×10 two layer board. 4 layer is also something accessible.
I want to share with you this experience, because, I had a good and an bad experience to share.
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