Well After working on the thing for two months, I’ve got a pretty good concept on what I want to achieve.
I started with DED and grew from there.
The first obvious “victim” was the FFI, as it’s “right there”.
followed by the Indexers (again, “they are just there”).
then I just got greedy 🙂
PFL was next to be added – because “it’s basically just another DED”, closly followed by the caution panel “it’s right next to the PFL, and the code is just a bumped up Indexer”
and then I completely lost it..
and glareshield lights and TWP lights were also included on the roadmap and also the CMDS display – because I can.
But I’m pretty sure the Arduino cannot handle all of this – at least the base would be set for floks that would prefer having TWP over caution panel or CMDS over DED/PFL.
but connecting everything is not as trivial, especially in the cockpit environment – and bread board is out of the question of course.. cables are too fiddly.
So I’ve started thinking about a PCB design to accommodate all this and make it somewhat user friendly to assemble – but still maintain some flexibility.
So that would be covered in this post.
The Arduino micro is very Breadboard friendly, it plugs in nicely into one and allows a very easy connections, As I’m using one, I’ve figured that mounting one directly on the PCB via the use of a female headers would be a neat trick – it will allow me to easily plug a Micro into place – And in future time, if needed, I can build an adapter that will take whatever device I’ll opt to use and re-use the existing hardware. the length and width of the headers I need are known and fixed – So the board layout starts with them.
Next is the connectors,
Most of the things I use are SPI controlled.
There are two types of SPI, 3 Wire and 4 wire SPI
I2C protocol (if I choose to use one) takes only 2 wires.
add 5V and GND – to a total of 6 wires. the is the max connector size I need. using 6 pin connectors will allow easy deployment, and will prevent wiring errors between the boards – assuming I can get it wired correctly in the first place.
I’ve decided to separate the everything into boards – each initially was planned to be 5cm by 7cm as it is the most common Prototyping PCB on ebay (and fits within the size constrains of the free version of eagle). And I chose to start with defining the basic functionality – DED, FFI and Indexers.
- Main Board – WIll mount the Arduino Micro, and will contain 6 pin connectors to the different pieces
- Indexers board – I initially wanted to put it on the main board, but it proved too much to compress onto the initial planned 7×5 size. so it got split into a different board – and there are of course the two Indexers I’ve already hand wired and shown in the previous post.
- display adapters – the screens have their pinout – the FFI has 8 pins, the DED/PFL have 16 pin (8×2) so I need to make an adapter for the screen
I’ve started looking into getting those PCB produced – and I’m looking into some cheap PCB manufacturing. But for now – these are two samples of the PCB concepts – main board and DED screnn adapter.
The PCB designs and schematics will be published along with the code later down the road (after they are properly tested)
Uri