Hello everyone,
I'm newbie about Arduinos but have already quiet a long experience on PLC's.
I'm thinking about a project to display informations from two ARDUINOS on one SPI TFT. This project should take place on the Dashboard of a 1970 Land Rover Series 2a I'm going to rebuild.
In fact, I plan to display on one half of the TFT informations from the first Arduino and on the second half from the second Arduino.
Theoreticaly it seems possible.
If I use the CS (one digital output) from the first Arduino to select the display and to prevent the second Arduino to write (thru a digital input of the second one receiving the same CS). I will do the same for the second one.
I also plan to put a schotkky diode on each CS signal from the Arduinos before entering the CS on the TFT display to prevent reinjection.
There is a scheme of what I'm thinking about.
Does anyone have already try such a solution?
FIST, WAS THE SCREAMING REALLY NECESSARY!?!?
Belfalcon:
Theoreticaly it seems possible.
But in practice, very impractical. For example, what about the data pins? What about keeping it in sync?
But let's start more basic, why do you think you need two Arduino's?
Sorry, screaming was not necessary, don't mind that it could disturb anyone.
I'm aware about the data pins, but as you cand see it in "screaming" title, we are speaking about SPI display, that means 3 max 4 pins for datas, clock, ...
I need at least 2 arduinos because :
one will receive informations about temperatures (out, water,oil BS18B20 +alarms), oil pessure (+ alarm), RPM from alternator, ambiant light for automatic headlights power on/off, ...
the second will received information about a coding disc on the rear transmission axle (to calculate speed, distance), impulses from a gear flow sensor meter (to calculate fuel instantanous consumption, average fuel consumption, range or autonomy), fuel level with alarm. This one will also save data's on eeprom
and as you seem curious there will also be other arduinos (mini's or nano's) for automatic screen wiper, automatic 3 operation cycles direction indicators and warning, ....
So now I think that you could understand why I need more than one arduino!
I'm not sure all that was really necessary to have an answer to my qustion !
Regards.
Life is MUCH simpler if you use a single MCU with sufficient legs.
A Uno can cope with multiple I2C sensors, multiple SPI sensors, SPI display, ...
Sometimes it might be convenient to use a separate MCU for a "local" job that uses many pins.
And let your main MCU talk to this external board as if it is another Slave "sensor".
You just have to sit down with a blank sheet of paper and draw up your design.
David.
I don't see anything in particular that would stop you from using a single Arduino. Maybe a bit faster one is beneficial but it does not sound impossible for a single Nano even. You could use an ESP8622 (but IO is a bit limited) or ESP32. And I think the support for the STM32 has come a long way as well.
But if you want to go with two, just let one take control of the screen and just push the data between them via for example I2C.
Set up one Arduino as the master that handles rendering whatever to the display.
If you want to display data from other Arduinos, connect them to the master through the serial pins and have them pass information to the master that then handles displaying it.
The advantage of using a single Arduino to render and serially connected Arduinos to send it data is that it's more extensible in the future.
You can have wirelessly connected Arduinos passing data to the master through something like XBees.
Trying to have two Arduinos control one display is just going to cause problems.