DIY remote design inputs

Hi guys
I’m fidling with a new design for a remote…
I have so far planned on using the following parts:
Arduino mini pro
0.96" OLED with i2c or spi
HC05 (bluetooth module)
18650 (single cell)
some sort of lithium charging circuit (ebay have some cheap)

My current design looks like this:

It is missing the dead-man-switch…

What would you like to have on a remote, if you could add things ?

4 Likes

Please do not use bluetooth for the transmission of the control signal, it has proven to be unreliable.
A remote that drops out and tries to kill you is not what we need in a sport this dangerous.
If you can fit a 2.4ghz transmitter (e.g. the NRF24L01), it would be more reliable.

EDIT:
Maybe you wanto to refer to this thread:

100% Realiability is the No.1 requested “Feature”

If i designed a controller it would have two 2.4ghz radio modules, both paired all the time and they would act as redundant radios so even if one radio disconnects the other is fine. I would also add a small spring actuated switch to the front that would control turn signals, and one button on the side for headlights.

2 Likes

You dont need 2 radio modules, just a receiver that handles dropouts properly

1 Like

since when is redundant design a bad idea? Especially when i’m trusting my life to a board, i’ll keep my two radios.

Yup, well beyond everything else is reliability. I’d pay twice the price in a heartbeat for a more reliable remote.

Besides that, I like the thumb slider switches and a battery level indicator.

1 Like

Battery level for the board?

That would need Bluetooth.

I am thinking, a Bluetooth and 2.4ghz transmitter. So you can easily integrate data and have a reliable remote.

Battery level for the remote only. I’m fine with just the level on the board. My EGO has an indicator and it comes in handy.

So far, my favorite remote has been the EGO remote. I don’t need the sport/rabbit modes of flash light, but I like the slim design. So far, I’ve never had a single drop out on that remote.

We might as well make a smart remote if we are going to spend the time making a custom one anyways. I am going to try and mod my Mini Remote into a thumb one with bluetooth.

1 Like

Then you’ll need 2 receiver modules too…

ok so then i need two receivers. A 2.4ghz radio chip is like 4 dollars. The electronic guts of a remote could be under $30 even with dual radios if you did a custom circuit. When i’m done with college this summer i will be making my own.

1 Like

I have NRF24L01 aswell, but why do you think its more reliable ?
I think 2.4Ghz is still 2.4Ghz… is it the BT handshake thats to slow to recover well ?

@B4Me

I’ve been working on a custom remote myself - but from a different angle so far. I have focused on the schematics and electric side. I am looking for other people that might be interested in teaming up and working together on the remote.
On my side, the main schematics (with charging circuit, usb2mc connection and other things) is done, but I haven’t had the time (and skill) to start with a case. I’d like to have the case first, in order to fit in the pcb (and create a layout on top of it)

Anyhow - if you are interested let me know.

Per your design - some suggestions from what I have gathered myself:

  • dead man`s switch (from what you already noted)

  • some menu button(s) to navigate and change settings

  • you might think of moving the display further down / towards the bottom. Most oled display have a fairly large pcb themself (usually around 3x3cm) and thus your display would most likely be taking space from the throttle system

@flatsp0t @Stevemk14ebr @Mrmoonlight @Pantologist

All your solutions mentioned work in the 2.4 ghz spectrum (actually 2400Mhz - 25xx Mhz) and they would all be prone to the same problems in urban areas. Just because you name it differently and have a different specification, doesn`t mean that there is suddenly more “space” in the medium. They all have to share the 2.4Ghz band (see wiki). So even if you include a second radio, you will need to deal with interferences. Your everyday 2.4 GHZ hobby remote is not built to be used in highly con-quested areas - and on top of that - the protocols are fairly simple and will not deal with packet loss / re-transmissions (/ encryption).

So where to go from here?

  • choose a different frequency band: go for 433MHZ or 868/933MHZ ISM bands. Even though you will have lower bandwith - it is vastly sufficient for realtime data from the vesc and from the remote. (100hz for controls and 10hz or less for displaying information is more than sufficient - assuming that control data is ~10 bytes (one axis, 1 button) and vesc information ~300 byte - we would need less than 5kb/s constant data connection ;-))
    The benefits are, that these frequencies are less common and used - so less prone to con-question and other problems

  • choose a specification that handles packet collisions, re-transmissions, con-question, channel/frequency switching reasonably well (from all mentioned actually wifi has the best specifications - highest transmision power (compared to bluetooth), low latency transmissions, encryption with wpa(2) etc.)

  • write your own protocol on top of a low level protocol (i.e. most 2.4 GHZ transceivers) to deal with mentioned issues

  • write your application to actually account for packet loss, re-transmissions and include proper safeguards.

Whatever you do, I can only recommend not to neglect the security issue with transmitting unencrypted data for your boards. Even if your data is encrypted, you should also account for packet replay attacks and other malicious attacks - it is your life you are dealing with here. And creating a harmful device is fairly easy. (Even if it is just to jam signals … )

2 Likes

I like the idea, but if you want redundancy, it should NEVER be on the same frequency… then you would want 2.4G and 5Ghz… or 868Mhz, you get where I’m going… having the same frequency, will make matters worse for both radios… and if the 2.4ghz is flodded due to wifi or some other thing… everything is dead now

You are a very gifted guy ! I must say…
I am my self a civil engineer, mechatronic master degree (software, mechanical and electronics)…
You have some excellent points in the things you are saying… I have decided on NOT to make the PCB’s from scratch (atm)… I design PCB at work, so at home I mostly rely on ebay and kits, there are so many dev boards out there :slight_smile:
Hope you get what I mean… I dont dislike the PCB design, but it is not necessary unless you are thinking about mass production, or like the finished feeling of a PCB :slight_smile:
If you can come up with a case design idea, and measurements or step files for internal components, I will definitely help designing your case :slight_smile:

I actually have some RFM12 modules (433Mhz), every car owner will hate me driving by (should use that frequency on car locks :smiley: )
But maybe thats the way to go, or on the skateboard I could have both BT and 433, then I could get more info on BT and less for the 433 remote :slight_smile:
But as stated by you, security is key, and fall back strategies…
eg. slow down and stop if signal is lossed, some encryption, or and incrementing number so playback attacks cant happen as easy that is…

But on the OLED I want things like:
Batt level
Watt (in or out and amount)
Wh used/left
Kmt or RPM (same same if you know the gearing and wheel dia)
remote battery level

1 Like

The display position is indeed where it needs to be atm :slight_smile:
… or maybe I will make the remote 5 mm higher, to push battery and oled down, as I have some hard time to place the counter part for the rotating rod in the top cover

3 Likes

Thanks for the compliments - everyone has something he likes to dive into when doing things. That`s why I like communities - people get together to exchange ideas and discuss and then something will evolve from that.

So anyhow - just a short response:

I understand where you are coming from in regards of pcb design - to be honest - these days ordering pcb prototypes (in small quantities) from china is quite reasonable. I like to tailor things to my needs (luckily I am not doing this at work - so I guess that is why I like to do them in my free time). I feel that the remote will be a “tight fit” and thus I thought about creating a PCB (also allows for choosing components :wink: )

And it doesn`t need to be mass production - but if there are more people interested in the pcb - there is always the option of doing a group buy (but people will need to assemble themselves).

Even your 433Mhz is plenty of bandwith - the data from the vesc to the remote doesn`t have to be very frequent (10hz or less is enough) - in my concept, I was planning to let the remote “stay dumb” when it comes to sending the information. From my point of view, just sending the position and state of the trigger is sufficient and requires just a few bytes -> low bandwith. It adds the benefit that the receiving controller (or the controller on the vesc) will be able to deal smoothly with dropped/lost packets and act accordingly to safeguard. It might be again overkill to have both bluetooth and 433 in the remote. (On the receiver side there it might be an option to connect via smartphones/laptops for changing vesc settings)

Looking at the exploded view, I can see why you moved the display to the top section. My take on this: don`t make the case too thick - it will feel more heavy in the end, than it actually is. Is there any particular reason for going with 18650 cells over a lipo flat pack? (Having a good charging ic (i.e. max1555), and a protection/undervolt circuit you can keep them in safe operating zones)

Oh and forgot to say: you might consider going up from 433 mhz to 868/933 mhz - 433mhz antennas will be quite large - that’s whats keeping me from choosing 433 so far

Is it like 12CM long ? it dosnt need to be a wip antenna, it could be pig tail design (coiled wire)
Or a pcb antenna … lay it down aside the hand

1 Like

I will admit the fealing of your own PCB is awesome ! but sparetime is key… and there exist so many dev boards where only the wires between is missing :smiley:
Maybe I will design a pcb if the prototype works :slight_smile:

I also think 433-868 is a good choice after the 2.4ghz discussion, as the frequency is NOT flooded, at least in europe, I think both a illegal to transmit over 1-2% duty, so it’s like a change of 1-2% to get noise from other sources on these frequencies :slight_smile:

The idea with BT and 433 was just to have the remote ONLY 433, but my phone of home could get diagnostics out of the board… and should the remote fail, an app could get the board running the way home :smiley:

18650 was due to the easy access, go to a dumbster, grab nearest laptop battery, 5-7 good cels out of 6-8 batteries
I have a lumber hand (some would say… :stuck_out_tongue: )
So I dont wont to make the remote to flat, it will end giving me some pain in the hand (hard to explain in english… but if you hold on something flat and thin for a long time, my fingers/palm is in pain…)
Therefor the 18650 was good capacity and size when I anyways want the fat grip (it is only 20mm thick 18mm battery dia + 2x1mm plastic)