I have a strong feeling that I got the wrong diode for the rectification of the triangular wave that comes out after the capacitive sensor (RC circuit). I got this one:
In the datasheet it says that this diode has a Typical Junction Capacitance of between 90 and 110 pF which seems pretty high compared to the capacitance of the sensor. Do I need a diode with a lower capacitance?
Can someone give me a hint if I am on the right track?
Edit: Okey I switched the smd diode with an all purpose tht diode that I had lying around and now the voltage swing is already at 1.1V so it definitely is the diode. Any recommendations on diode selection for high frequency (1-4MHz) applications?
@alowhum There will be a wealth of information out there on the net and probably also at your local library. look for resources about remote cabin power systems and also even the larger 5th wheeler type caravan systems will be helpful reading. You will also need to check your local building codes to see if there are any rules to be adhered to.
When we built our house (about 15 years ago, long before i discovered MySensors we ran a low voltage backbone cable throughout the house. From this backbone we ran smaller cable drops to every room in the house. Many of these are still not in use but as others have said the cost of running wires is relatively cheap when you are building. Of course we still have mains power as well and use the low voltage system to compliment this.
In those initial years the 12v system was used primarily for lighting systems such as night lights etc. As time progressed we installed 12v outlets in the bedrooms and these now are used to power bed/reading lamps. The small 12v downlights have also proved to be very easy to convert over as well. These were initially halogen bulbs but now there is a good range 12v LED replacements for just about any type of socket. Once I discovered MySensors and home automation then the 12v system became even more useful now powering several nodes and even the gateway.
Right from the start we ran our system from a battery with solar charging and in 15 years it has never let us down. Voltage drop will always be a thing to watch, but with LED's low power draw and as you have surmised the ability of arduinos to run well below 12v it will usually be of little practical concern. Unless of course you are thinking of running more than lights and nodes.
@eiten Yep, already saw this one. Based on the heltec implementation, the sx-registers are mapped to specific memory regions of the mcu. Would be interesting to have here a complete ASR-specific documentation...
As you're really interested in Nordic nRF52840 and nRF52832, I can't prevent myself from suggesting you to have a look at this project where I used a mesh of low power sensors with two types of dongles UART and native USB.
I do not place this project as alternative to MySensors as it does not have the same goal at all (no community, not many sensors), it's very custom, but the advantage is flexibility in case someone wants to be closer to the official nRF SDK, as that's my sole dependency and it is not using softdevices so leaves freedom to use priviledges and inetrrupts as needed.
I've been actively looking for standardised method to fulfill low power sensors, mesh network with OTA update. And the way there seems clear but very slow. only nRF52840 supports zigbee, and you need a custom zigbee to MQTT for each network. I have hopes that Thread (OpenThread) will resolve this, but thread is too experimental at the moment and 0 commercial sensors compare to all zigbee sensors available on the market.
So I guess, the radio choice for you will depend if you target a commercially supported project which has a development budget or a DIY plan, also how much effort is intended to be spent on custom sensors creation compared to using low cost existing ones. I realised that I can't make DIY sensors cheaper than the existing zigbee one, which breakes the goal of the DIY model unless you do it for learning purpose or for fun.
I'm checked the micro python / circuit python, but that's also a slow evolving path where it's not the HW supplier that's worried about porting the drivers but a third party have them limited to some peripherals.
Nordic has OTA examples since the very first SDK of nRF5xxx, but it's way challenging to bring it to a seemless user product, just configuring nRF compile flags is quite complicated.
I'll keep watching this forum closely and be happ to see a working solution with nRF52xxx, I do have x5 of those nRF52840 usb dongles.