Arduino AIO Darkroom Timer

[koraks]

You're welcome The LCD should work with the backpack added to it. Keep in mind it needs to be soldered onto the LCD. I've seen people just 'plugging' it in with pin headers, expecting it to work that way.

 

[albada]

Just to add my 2cts to this one: I've also searched for a bit for something like this, but 20x4 is a bit less common than 16x2 to begin with, and we tend to get them in only a few default color schemes. For my enlarger controller I ended up picking any old black-text-on-white-background 20x4 LCD and modify it with a custom backlight. It turns out that the backlight is generally one or two blue or white LEDs that shine into the narrow sides of the LCD itself. Replace these with any color you like, or even RGB LEDs. If you want to go fancy, you can even add a little pwm module (just a small signal mosfet and two resistors, basically) to make the backlight dimmable from one of the Arduino's pwm pins.

I'll add that LCD modules have two types:

Transflective - the background glows and the letters are black.​

Transmissive - The background is black and the letters glow.​

Get a transmissive module! Glowing letters emit less light into your darkroom than a glowing background because letters have less surface-area.

Mark

 

[koraks]

@albada I think the transflective ones are more common, though. I haven't bought LCD's in a while to be honest...
I'm also not sure if the transmissive ones are as easy to hack in the way I described. They do look nicer overall, but back when I was doing my enlarger project, I couldn't find any in the dimensions I was looking for.

I did consider just using an ePaper display and shine a little light onto it, but the refresh rate was bothering me. Later on I did a project that confirmed that an ePaper would be too slow for this (even using partial refresh). Let's hope they speed up a little, as they would be quite nice for darkroom work.

 

[snusmumriken]

I hadn’t noticed this thread before today. Having a little experience of designing Arduino gadgetry during my career in wildlife biology, I had often considered building a timer/light controller. Reckoned it might even get me into f-stop printing. Seeing the fate of this thread, I feel quite glad I didn’t bother! I get on fine with a Soviet-era Czech clockwork enlarger timer.

 

[koraks]

Projects like these are great fun - but can be a black hole for free time as well

 

[alanbradford]

OK - Finally got the rotary encoder and can confirm that the changes Koraks suggested to the original code (above) work perfectly and without any issues I have seen so far. Photo of finished device attached. Thanks so much Koraks!

 

[koraks]

Oh, that's so cool! Thanks for confirming that the solution works - have fun with the device

 

[Olivierbl]

Hello,
I tried to built this project but i have some errors.
I used an Arduino Uno (no generic or clone)
I used the arduino librairy :
- LiquidCrystal (1.1.1 and 1.1.2) from Frank de Brabander
- Keypad from Mark Stanley (3.1.1)

I changed the arduino code like "Koraks" said. I changed the line 56 by the following command :
LiquidCrystal_I2C lcd(0x27,20,4);
and also i replaced the line "186" by lcd.init();
I removed the line :
lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

I followed the connection between all composant with the PDF schema and it's correct.

But my problem is my LCD, no menu display, LCD flashe every one second.

I tried with an example to display "Hello World" on the LCD and it's working, but when i put the code in arduino, LCD flashe

I don't understand...

@alanbradford how do you create your project ? can you share the code ?

Thank you

 

[koraks]

LCD flashe every one second.

Can you describe in more detail what you mean?
Does the backlight flash every second? Or is there some kind of text or symbols on the LCD that appear briefly? If so, what exactly?
By flashing every second, do you mean something is 'on' for a second and then 'off' for a second? Or does something briefly blink every second?
Perhaps a photo might help.

 

[Olivierbl]

Can you describe in more detail what you mean?
Does the backlight flash every second? Or is there some kind of text or symbols on the LCD that appear briefly? If so, what exactly?
By flashing every second, do you mean something is 'on' for a second and then 'off' for a second? Or does something briefly blink every second?
Perhaps a photo might help.

Thanks Koraks for your help and answer.
No letter appears on the LCD, all blocks blynk every second
in below two photos.

And if load the following program it's working:
#include <Math.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,20,4);
void setup() {
lcd.init();
lcd.setBacklight(HIGH);
lcd.home();
}
void loop() {
lcd.setCursor(0,0);
lcd.print("Hello World");
lcd.setCursor(0,1);
lcd.print("Olivier");
lcd.setCursor(0,2);
lcd.print("DARKROOM Olivier");
lcd.setCursor(0,3);
lcd.print("Leica iiiG");
}

 

[koraks]

Thanks, that's much clearer. Could you upload the full code of the darkroom timer sketch as you've used it (unsuccessfully so far) in your device? My expectation is that there's a minor error somewhere in the first part of the code, in the constructor for the LCD object or in the setup routine.

 

[Olivierbl]

Thanks, that's much clearer. Could you upload the full code of the darkroom timer sketch as you've used it (unsuccessfully so far) in your device? My expectation is that there's a minor error somewhere in the first part of the code, in the constructor for the LCD object or in the setup routine.

This is the code that i used.
It's the same like the original but with your recommandation to change 2 lines.
Thanks very much

 

[koraks]

I can see no problem with the code on a quick inspection, but I suspect something else is amiss.

Can you disconnect the relay module from your project and then run the same code again? Disconnect everything related to the relays; power supply lines as well as control/gpio pin lines. See how it runs that way. I have a suspicion you have a power supply issue, resulting in your Arduino being stuck in a reboot loop.

 

[Olivierbl]

I unplug the relay module but same problem.

On the void setup option, i comment the line from 195 to 219
(
//Setups the rotary encoder for interrupt -->
safelightState = HIGH; //turn safelight on on start - just change this at initiation )

My LCD not blynk and i can see now the menu, as i comment some variable or instruction, the programm doesn't work

 

[Olivierbl]

OHHHHH i think i found my problem !!!
I comment the session
//Setup for push switchs on pin 13 and 15

This section is for interrupt and maybe i have some error on my connection with the switch.

 

[koraks]

Yes, that sounds likely. Good job tracking doen the problem!

 

[Olivierbl]

Yes, that sounds likely. Good job tracking doen the problem!

it's thanks to you, you put me on the right track

When the project will be finished i will post some photos and my opinion about this

 

[alanbradford]

Only just seen this - Here is the code I use that works - Alan