start78
Posts: 42
Joined: Mon May 23, 2016 8:02 am
Location: Germany

Display for alarm clock

Mon Sep 19, 2016 11:47 pm

I'm planning to build a simple alarm clock (show time, at least 2 alarms, play mp3 sound).
My first hardware problem is the display. I'd like to use a 3,5" lcd graphics display. Doesn't have to be a touchscreen.
But: most of them connect to the gpio. I need to add some buttons for the settings. Is there a small, affordable display that connects to the RasPi display port?
And: it should be possible to set the display to be realy dark but still readable during the night and day. Even most commercial alarm clocks are way to bright for a bedroom.

stderr
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Joined: Sat Dec 01, 2012 11:29 pm

Re: Display for alarm clock

Tue Sep 20, 2016 12:39 am

start78 wrote:Even most commercial alarm clocks are way to bright for a bedroom.
If you used LEDs, you could dim them for the conditions as you see fit. The LCD would likely have a backlight and those can be trouble making them light enough to see without being too light.

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DougieLawson
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Re: Display for alarm clock

Tue Sep 20, 2016 10:04 am

Most things which use an LED for the display, or LEDs as backlights can be driven with PWM, that's an effective way to dim LEDs. You simply vary the duty cycle. GPIO 18 does hardware PWM.
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start78
Posts: 42
Joined: Mon May 23, 2016 8:02 am
Location: Germany

Re: Display for alarm clock

Tue Sep 20, 2016 2:11 pm

So much for the brightness. Thanks!

But now i need actual recommendations:
Does anyone know of a cheap display that leaves the possibility to add some buttons to the gpio port? I need at least a snooze-button (maybe an arcade switch?) and two or three settings buttons.

I wanted to keep the costs under 70 Euros. Used RaSPi B+ (because of the bigger gpio port) + AC_Adapter + wifi (7€) + case + Speakers (10€)... Doesn't leave much for the display...

tinylcd
Posts: 206
Joined: Sat Oct 26, 2013 4:07 am

Re: Display for alarm clock

Wed Sep 21, 2016 4:29 am

hello

below are few options see if they can meet your budget . the spare gpio are avaibable on the 26/40 pin header pcb

3.5 inch with 26 pin gpio header pcb
http://www.neosecsolutions.com//product ... 8&cPath=17

3.5 inch with 40 pin gpio header pcb
http://www.neosecsolutions.com//product ... 2&cPath=20

2.8 inch with 40 pin gpio header pcb
http://www.neosecsolutions.com//product ... 8&cPath=20

regards
tinylcd

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