This looks very excellent! I like the “pocket-able” design criteria.
Update:
Lora Conduction Test
Summary
When TX set to 20dBm, the RF output power was 19.5dBm
When TX set to 14dBm, the RF output power was 15.5dBm
Conclusion:
The insertion loss of the test results is equal to or better than the theoretical design. Therefore, the chip SX1276 do has capability to transmit 20dBm with only 0.5dB insertion loss.
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What hardware are you using to measure this?
I used RF Explorer 6G COMBO+ for this experiment.
RF Explorer 6G COMBO+ is a Spectrum Analyzer, covering the full 6GHz range starting at 50KHz up to 6.1GHz with no gaps or limitations.
I had compared RF Explorer 6G COMBO+ with our Tektronix MDO3104’s spectrum analyzer function. The accuracy of the RF Explorer 6G COMBO+ is very good, and the size is very portable and can easily fit into a backpack.
The main downside I feel is that the scanning speed is much slower than professional equipment. Especially when debugging a UWB device and need to scan a relatively wide frequency band. But for the price, I have no reason to complain.
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Bigger display.
To let the unit work as standalone device for elderly or people without smartphones.
When 2 devices needed, also need to charge 2 devices 
stand alone only need charging/power to one device
All seem to be in “flow” development 
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Also use de RF explorer and Adalm Pluto SDR to 6 GHz and real spectrum analyser.
@Neil This looks great, really nice to see some open(ish) hardware!
Have you decided how to license it? By default, it seems to be attribution-NC? Would you consider something like CERN-P?
Do you think it’s worth exploring an ESP32-C3 version? It would drop a couple of dollars from the BOM & I think save a bit of power?
However, I don’t know if anyone has Meshtastic on a C3 yet?
At 450 dollars, it’s more than I am willing to spend right now. Does the NanoVNA measure the RF output power?
NanoVNA can not measure external signals.
Oh, you may interest in tinySA project, it is much cheaper and still covers all lora bands, except 2.4GHz.
So sorry for the late reply, I just moved from one city to another and moving is always a hassle.
There is no way I can do RF projects to meet commercial standards without the support from my colleagues and lab, this is why I currently have to use an NC license.
I need supercomputers, commercial softwares, professional equipments from Keysight, Tektronix, Rohde Schwarz to complete the design, and I also hope that the design will be attractive to my colleagues in the lab who are willing to put in the time to perfect it. One day low-cost instruments can replace commercial tools, NC license should not be necessary anymore.
Of course, I will try to use the simplest and lowest cost equipment possible to illustrate the design idea behind the project, which should be the value of this design without touching the non-disclosure agreement.
I’ve used ESP32-C3 for a while, and I feel the biggest advantage is that the latest version has a built-in USB to UART bridge.
However, it seems that the Firmware of the meshtastic project does not support C3 yet, and some porting work should be needed.
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The Nano Edition G1 is already in production at the factory, and I’m testing an engineering prototype in the new city. The impact of the urban environment on the US band is still relatively siginificant.
I noticed that Medium/Slow could be the best balance between RF coverage and user experience, at least for the current firmware. The experience of Long/Slow is actually not good, because it is easy to time out when sending messages continuously.
3 Likes
I really like how this is progressing. Thank you for the work you have put into it.
My wish list, and maybe it would be a good idea to do a poll of some sort to see what other think, is as follows:
Rotary encoder for ‘canned messages’ see this thread Should not take much space and they seem cheep compared to the functions they allow. Could even replace the current user button as long as the rotation and press circuits are used. I think having a (Button RE Button) arrangement would make for a much improved user interface. Using RGB led backlit buttons could be an extra ‘wow factor’ as the rgb led can provide feedback / notifications. See this
Larger display - Possibly e-ink. Could be well worth the community effort to track down the ideal cost / size / quality / power required screen options. As well as it works I think there are several compromises made on the software and interface side due to the common, but small screens.
Temperature, Humidity, Pressure sensor - This would be a cool add on feature if it could be included for minimal additional costs. When these devices are used for relays this is often useful information for the node operator. But… It can also be useful for hikers to understand current environmental factors and with relatively simple code could show trends in changes and that is essentially a simple weather station that can be used to anticipate sudden changes in weather, like an incoming storm. For one of the original use cases, paragliding (and related flying) it is also very useful. Especially if we can use the SPI flash to store data logs.
Solar capable Battery Management System - It seems like for a small increase in cost a BMS that can accept usb and solar is possible. See this This can make solar charging much more accessible.
4 Likes
Ah, that’s a shame. Are you planning to mass-produce this for profit?
It’s unclear otherwise how an NC licence provides any tangible benefit to your colleagues?
I noticed the rotary encoder about one month ago, the idea is wonderful, however I still could not find out any smaller encoder which could fit into my design’s shell. What about the Thumb-wheel three-way Multi-function switch K1-1502SA-04 (https://www.aliexpress.com/i/4000946822824.html) which is used for NanoVNA, it comes with push right/left, and push down function.This switch is also thinner and can use the SMT process.
E-ink screens are usually more expensive than OLEDs for the same size because the market demand is too small.
Even if cost isn’t an issue, I’m wondering what a big screen can bring. Maybe I still need to use meshtastic for a while to understand the role of the big screen.
One possibility that I think is that if use a larger LCD screen and a physical keyboard, after porting the LVGL Library, global languages and input can be supported. But such design would raise the hardware cost so much, I don’t know if it’s worth it, especially in an age where everyone owns a phone.
For the sensors, from the perspective of system architecture, does it mean that we should support RS485 or CAN bus in order to connect any kind of sensor node?
For the solar, I know CN3791 MPPT charge controller could do job, however, I originally imaged the BMS as an add-on component, connected to the device via USB type C, the simplest BMS could be a small power bank. The reason for this is I want the device could be easily carried on the plane, and lithium batteries are often restricted from TSA’s screening procedures. Foreign airports sometimes have stricter restrictions on lithium batteries.
Briefly, Yes, this design will be mass-produced. If the design goal is Optimized RF Design for Maximum Coverage, mass production is currently the best way to distribute this idea.
==============
NC license is a long story. Many years ago I wrote an article about how to design ACDC to achieve continuous operation for more than 10 years (https://uniteng.com/index.php/2019/11/14/lnk3205/), and pass UL certification. I needed to use the design from our lab as an example, the result of discussions with the co-founders was that I could write an article explaining the design idea, but the article had to be reviewed.
The reviewed articles can be used freely by readers, including commercial use, but the design reference (PCB layout, etc.) must be under NC license and cannot be directly commercialized. Therefore, the NC license is just a tradition, and projects that use Lab resources generally continue to use the NC license.
For analog, especially RF projects, I don’t think the license is the biggest problem. In fact, if the goal is “Optimized RF Design for Maximum Coverage”, it is always difficult to reproduce the performance even with complete design data.
The most important thing here is process control. Each batch of componments is slightly different and needs to be tested, modeled, and tunned. In our lab this process requires a lot of expensive equipments, cross-licensing and proprietary intellectual property. PCB fabrication also requires to use the same Core and Prepreg, the same layout, pressure and temperature. These parameters are different for each factory and need to be adjusted on a case-by-case basis. Because resin bleed-out during the curing process, this will seriously affect the RF parameters of the PCB.
More details:
The Considerations of Antenna Design for IOT and Wearable Devices
https://uniteng.com/index.php/2019/11/20/the-considerations-of-antenna-design-for-iot-and-wearable-devices/
In the end, I think the most important thing is to produce a good RF product. Commercializing this hardware is also more sustainable. For the hardware community, I will try to describe the design ideas clearly. Hope the meshtastic community can have a Paypal for accepting donations, we also hope to donate to every product sale with pre-installed meshtastic firmware.
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Ah great, if you are commercialising then it’s a reasonable position.
I do get frustrated when people slap an NC on for no particular reason, but I guess it makes sense here.
I’d buy the waterproof version with wireless charging.
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Update:
Just finished the Wiki for the Nano Edition G1.
https://uniteng.com/wiki/doku.php?id=meshtastic:nano
It is time to pay more attentions to the Station Edition 
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Ohhh, very nice, shiny even (for Firefly fans). I’m trying to imagine placement, on the side? How would you comfortably hold the device and use it, ideally while having good view of the screen. Probably a lot to ask but having two, arranged so you could hold and press like an old game controller would be very cool maybe something like this…
About the screen, and people using phones. Smartphones are common except for places where they are not. And using a phone as an interface is convenient for situations where they aren’t.
Would using a phone be save / convenient when doing this?
Could these devices be donated to places like this without the added cost of smartphones and the added charging / support required for the phone?
If you are doing something like this how long does the phone battery last, or how big of a solar charge would you need to recharge a Meshtastic device + phone vs just the Meshtastic device.
About the battery, I think it would be great if there was enough space to easy add / remove a battery like this:
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I will keep in mind to add Multi-function switch to the pro edition with 1-4W adjustable PA. I believe that professional fields require extremely reliable connections, so well designed antenna, rugged construction and increased transmit power are sometimes necessary.
For the Nano Edition which will be released at next month, its aims to provide a compact Lora device with high efficiency internal compact Lora PCB Antenna, ultra-low noise figure amplifier and internal GPS module with build in patch ceramic antenna. This series aims to balance the RF performance, size, rugged construction and power consumption. Nano Edition is generally an RF enhancement of existing device. More advanced features will be implemented in the Station and Pro edition.
Rome was not built in a day, when I use meshtastic for a while, I can slowly eliminate the stereotype and realize a lot of problems. Such as @hamradionl mentioned why bigger screen matters, the messages on the OLED screen are indeed small, and the current firmware cannot display the global language. Not everyone speaks English. Input will be a bigger problem than displaying the global language. That’s also why I haven’t moved to the nRF52840, the ESP32 does consume more power, but it has two MCU cores, which has more opportunity to implement complex UI.