meshtastic
Add support for a new nRF variant constructed by soldering an E22
module directly to a Pro Micro type nRF52840 board.
This variant supports the easy DIY pocket node which I have documented with detailed build instructions here: https://github.com/brad112358/easy_E22
This method of construction takes advantage of the flexible pin to function assignment the nRF52 offers to eliminate the need for a breadboard or custom PCB. The Ebyte E22 900M33S LoRa module is actually a very good fit for a battery powered device. The LNA and full 1 watt of output power it provides on 3.7 volts are significant advantages over the bare LoRa chip designs which are so common.
This is my first Meshtastic PR.
Thanks!
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I'm not sure why this got no attention for so long. Then I missed the stale label and now it's closed and it seems my previous comment asking why is also being ignored. This is very discouraging because I spent a lot of time developing detailed build instructions for this high power, easy DIY node with few wires and no custom PCB required because there don't seem to be many (any?) commercial 1 W mobile nodes.
(guessing now on who to ask) @vidplace7 @thebentern can this be re-opened? Do I need to open a new PR? Should I just give up?
Hi @brad112358 , I'm sorry your first patch to Meshtastic has been a bad experience.
The honest truth is, all of the people (volunteers) who could review and comment have just been very busy since August. We've been pushing hard to get a stable beta 2.7 release out, which has had some heavy lifts in areas like Bluetooth. DIY aficionados such as yourself are very important too, but we've just been focused on other things for a few months. I personally have a patch that's been waiting a similar time, so know how annoying this is!
@NomDeTom is an E22 expert, who might be able to take a look. Otherwise, the nrf52 channel in discord ha a wealth of knowledge, including people who might want to build one of your boards.
Sorry again, we're just swamped.
To make this easier to merge, would it be possible to change the base to the develop branch? Master is in a feature freeze right now while we work on the beta release.
I'm not sure why this got no attention for so long. Then I missed the stale label and now it's closed and it seems my previous comment asking why is also being ignored. This is very discouraging because I spent a lot of time developing detailed build instructions for this high power, easy DIY node with few wires and no custom PCB required because there don't seem to be many (any?) commercial 1 W mobile nodes.
If it helps, my group was hugely inspired by your work on this and we're planning to build a bunch of what we're calling Janktastic. https://www.reddit.com/r/meshtastic/comments/1oglyf3/my_pocket_node_1w_e22_radio_diy/
@fifieldt Thanks for re-opening this! I completely understand the development team being busy on higher priority work. I'll continue to try to be patient. My frustration wasn't so much with the delay as that I thought I was being patient on my end, but my patience was rewarded with the PR being closed by a impatient robot with no way for me to re-open.
I have changed the base of the PR to develop as requested. I've also taken this opportunity to rebase and squash commits.
@wlockwood Thanks for your supportive comment! I took a look at the nodes you have been building. This isn't the best place for a lengthy discussion of design choices, but I will point out a couple of observations which are also relevant here because they are reasons I need a new variant and can't use the existing nrf52_promicro_diy_tcxo as you are doing.
First, for a simple 1S Lipo or LiIon powered (no voltage boost) design with the goal of 1W output, you really need to use an E22-900M33S, not the slightly cheaper E22-900M30S which is supported by the existing variants and which you are using. This is because both versions of the E22 only reach close to their rated power when supplied with at least 5 volts and the 33S version comes much closer to it's rated output in the 3 to 4.1 volt range which is what both of our designs are supplying. The 30S version only outputs about 70mw at 3.0 volts (much lower than a bare SX chip!) and about 500mw at 4 volts. The 33S version outputs between about 500mw and 1.1 w in this voltage range, very close our goal of the maximum legal power.
Unfortunately, there is no way for the firmware to check which E22 variant is used so the pre-compiled firmware which Meshtastic provides for the nrf52_promicro_diy_tcxo variant does not support the 33S variant. In fact, if you attempt to use the 33S with this firmware, you will destroy it's power amp because the Meshtastic default power output setting is larger than the 8dBm maximum which the 33S allows!
I also wanted my design to be as simple to build as possible while not requiring a PCB. This is the second reason I couldn't use the existing variants as I wanted pin assignments which allow soldering the ProMicro and E22 directly together back to back.
In fact, if you attempt to use the 33S with this firmware, you will destroy it's power amp because the Meshtastic default power output setting is larger than the 8dBm maximum which the 33S allows!
If the output is so much lower on 3V but the MCU still works, could you do the initial boot and config on 3V, set the output level, then raise the power to 5V?
Also, thanks for your detailed response. I sent the link for this conversation to my group.
Also, thanks for your detailed response. I sent the link for this conversation to my group.
This isn't the best place for node design discussions. I've sent you an email. If you didn't receive it, let me know where I can contact you.
Another month has passed and I see a beta has been released. @NomDeTom Do you have time to review and comment on this PR?
I'll be honest, I forgot about this. I have been thinking about adding this pinout to the existing promicro variant.h and platform.ini, to keep it together with the existing files. @brad112358 how does that work for you?
I have been thinking about adding this pinout to the existing promicro variant.h and platform.ini, to keep it together with the existing files. @brad112358 how does that work for you?
Yes, I think I'd be happy with that, especially if this approach makes it easier to get to the point of the project providing pre-built firmware for this pinout. If only one pre-built firmware for this pinout is provided, I suggest that it needs have MAX_POWER set to 8. I think this is also a problem with the existing promicro firmware as it would be easy for a user to mistakenly use the pre-built firmware with an E22-900M33S and burn out the power amp.
ah, I don't think it will make it through to being officially built or in the flasher, but it will be very easy to make it using the github actions. See here: https://github.com/meshtastic/firmware/pull/8839
See here: #8839
Very cool. I didn't realize this build action existed and I'm not very familiar with github actions. Am I correct that this requires that a user have a github account and create their own fork to build a target?
How do you want to proceed? Should I modify this PR to integrate this pinout with the existing nrf52_promicro_diy_tcxo variant or would you prefer to do the work yourself? If you want me to do it, what should we name the new target(s)?
Am I correct that this requires that a user have a github account and create their own fork to build a target?
Yes, that's the idea.
How do you want to proceed? Should I modify this PR to integrate this pinout with the existing nrf52_promicro_diy_tcxo variant or would you prefer to do the work yourself? If you want me to do it, what should we name the new target(s)?
I'll try and make a pull request to your branch with the necessary changes, and then we'll go from there.