Mode Zero

I was talking to a friend yesterday evening and he asked if had any new projects I was working on. There are quite a few ongoing projects that I have never posted, so here is a preview of a couple that are nearing completion.

The first is what I have dubbed the GTN V2 encoder (the GTN V1 encoder encountered a few problems and was abandoned, but more on that later). I had been trying to squeeze as much onto a 40mmx40mm encoder board as possible (the same size as a Pro Mini Strong), but wondered what I could do with a board that was 40mmx20mm, half the size of a Pro Mini Strong. I wanted an encoder of similar performance and features of my range of encoders with an LCD, ie multi-model memory and most common computer transmitter features. I got to work with KiCAD and this is what I came up with with the computer-generated 3D image:


It uses an ATmega328PB-MU, a tiny 0.42" OLED, three programming switches, a diminutive sounder that only measures 5mmx5mm but is as load as the typical 12mm round sounders often used, a pot and zener diode for a full-scale-range meter and most of the connections via a 12-way JST-XH connector with a pre-wired plug with 20cm cable tails. This was ordered with JLCPCB and these arrived through the post:


I then assembled a few of them with different height tactile switches to see what height worked best. In production versions, I will use SMD tactile switches assembled at the factory to save me some soldering and cost.


So you can judge its size, here are two of them with a Pro Mini Strong.


Even though the OLED is tiny, it is very easy to read under normal lighting (but the same as any other OLED, not so good in direct sunlight).


The hardware specification is as follows:
● Compact 40mm x 20mm.
● 6.6V - 9.6V operation with reverse polarity protection.
● 0.42” OLED display with 10 characters x 3 rows of text (72x40 resolution ).
● The joysticks, auxiliary channels and switches are wired via a 12-way JST ZH connector with a 12-way plug with 20cm of cable pre-wired.
● Power in, PPM output and the meter are all standard 0.1" headers.
● On-board multi-tone alarm sounder.
● On-board Zener diode/potentiometer to re-use the original meter for an expanded scale battery indication .
And the firmware:
● 10 Model Memory.
● 9-character model names
● 8-Channels, Aileron left and right, Elevator, Rudder, Throttle, Aux1, Aux2 and Gear.
● Servo-reverse on all channels.
● End-point adjust on all channels (also called travel volume, servo travel adjust etc).
● Sub-trim on all channels.
● Trim on A, E and R with "Auto Trim" on a push switch
● Dual Rates/Expo on ailerons, elevator and rudder.
● Freely assignable channel output order
● Elevon and V-Tail mixing with adjustable mixing ratio.
● Aileron differential (user adjustable).
● Aileron to rudder mix, often called CAR (coupled ailerons/rudder).
● Knife edge compensation mix (rudder to aileron and rudder to elevator).
● Throttle to elevator/rudder/aileron mix (to allow for incorrect thrust line).
● Flap to elevator mix (to stop zooming when the flaps are lowered).
● Crow brake (also called butterfly) which raises aileron when flaps are dropped.
● Count-down timer controlled via throttle position or gear switch.
● Throttle cut (via the throttle cut switch).
● Power on “soft throttle lock”.
● Low voltage alarm (user adjustable alarm voltage).
● “Trim Alarm” if trims not centred when powering up or new model memory selected
● Inactivity alarm.
● JR or Futaba PPM "polarity" and channel order

If I have enough memory spare I will add free mixers, but I still have a bit more programming to do,

I have most finished with just a few of the mix functions still to complete, I can "borrow" the code from my LCD encoders for most, but I need to re-work the menus. Here it is connected to a ppm meter.


And the connections:

The next encoder off the production line is what I've called the GTT, the "T" is for tiny! It is the same dimensions as a Digispark with the USB cut off, but has more features, such as a full 8-channels. The boards have been ordered and I'm waiting for them to arrive from JLCPCB.

Similar to the GTN2, it has a 5mm sounder and a pot' and zener for an expanded scale meter and most of the connections are via a 12-way JST-ZH connector with a pre-wired plug and 20cm of cable. It will use the ATtiny1616 processor, one of the new generation from Atmel intended to replace the ageing ATtiny84 and ATtiny85. I'm using an Adafruit ATtiny1616 development board to get familiar with the ATtiny1616 and get ahead with the programming. The ATtiny has quite a few differences from the ATtiny85, it is smaller yet has 20 I/O pins, nearly as many as an ATmega328P. It does not have an xtal oscillator connections, so I'm using the internal oscillator which is a LOT more accurate than the ATtiny85. Finally, it is programmed by the newer UPDI single-pin programmer.

It will sell for less than my GTS encoder, yet come with cables long enough to reach most joysticks and switch connections and will fit just about in any proportional transmitter. Compared to the GTS encoder, it is only missing the rates/expo and aileron differential, it can do everything else.

The specification will include:

● Compact 20mm x 19mm.
● 7.2V - 9.6V operation with reverse polarity protection.
● The joysticks, auxiliary channels, switches and meter are wired via a 12-way JST ZH connector with a 12-way plug with 20cm of cable pre-wired.
● Power in and PPM output are standard 0.1" headers.
● On-board multi-tone alarm sounder.
● On-board Zener diode/potentiometer to re-use the original meter for an expanded scale battery indication.
And the firmware:
● 8-Channels, Aileron left and right, Elevator, Rudder, Throttle, Aux1, Aux2 and Gear.
● Servo-reverse on the Ailerons Left and Right, Elevator, Rudder and Throttle channels.
● Elevon or V-Tail mixer
● Count down timer (minute minder).
● Throttle cut (via the throttle cut switch).
● Power on “soft throttle lock”.
● Low voltage alarm (pre-set at 6.5V).
● “Trim Alarm” if trims are not centred when powering up.
● Inactivity alarm.

Very impressive Mike, well done - You are a boffin !!!

Great work Mike, great ideas, as Wayne said very impressive. Looking forward for more.

Brilliant work, Mike! That really is something to be proud of!

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Pete

Absolutely incredible! Please put me down for a GTN V2 as and when it becomes available......

Paul

Very impressive work.

Great work as ever, but I think you might have raised your lofty bar even higher now!?!

PS I couldnt find an emoji for Applause!?!