BuddyHolly7
Posts: 3
Joined: Sat Jul 24, 2021 6:42 pm

How do I combine several components to GPIO

Sat Jul 24, 2021 7:24 pm

Hi board!
I'm not new to the GREAT raspberry, but new to the board :-D
I currently use 3 RPI as media server, 3D print server and Homematic central at my home place and have installed two of them in a local pub (one as platform for SCOLIA darts and another one there to be used for digital signage purposes).

I now want to start a new project - making more use of the GPIO since now. I need to combine the following components:
- Raspberry 4 Model B 2GB (EAN/GTIN 0765756931175)
- Raspberry orig. 7'' display (EAN/GTIN 4250236811932)
both stored within the case
- Joy-it 7'' (EAN/GTIN 4250236820354)
together with the
- RPI RTC (EAN/GTIN 4251266700746)
and (in addition to the 7'' display)
- a Joy-it 2.6'' LCD-display 16x2 chr (EAN/GTIN 4250236813219)

The 2nd display will be connected via a separate 4pin connector socket - for which I will have to drill a hole into the nice case at a proper place. The RPI case will be then connected to the 2.6'' display via a cable of about 2m and the display itself will receive a customised case made by my 3D-printer.

My problem now is how to connect all these components to the GPIO. Including the cooling fan (which comes together with the RPI case (4250236811932), I will have to connect to the GPIO:
4x GND (all components)
1x 3.3V (RPI RTC)
3x 5V (7'' + 2.6'' displays + fan)
3x SDA (RPI RTC + 2x displays)
3x SCL (RPI RTC + 2x displays)

I checked on the web, but couldn't find any Y-connectors (or multiples) for the GPIO :-(
I would be happy if someone could give me a hint how to solve this practically.

Sorry for starting my first post to this board with such a weird question :-/ ;-)

Thanks in advance for your answers and stay healthy,
Buddy

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 14177
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: How do I combine several components to GPIO

Sat Jul 24, 2021 7:43 pm

Not a joke, but buy a soldering iron, and learn to solder, and you will never have a problem permanently connecting two metal wires together again.
Learning to solder is a must for every engineer. :mrgreen:

User avatar
scruss
Posts: 4361
Joined: Sat Jun 09, 2012 12:25 pm
Location: Toronto, ON
Contact: Website

Re: How do I combine several components to GPIO

Sat Jul 24, 2021 8:21 pm

So you want to attach:
  1. the Raspberry Pi Touch Display
  2. a 7“ LCD Display - Joy-IT HDMI display
  3. a Raspberry Pi - Real-Time Clock Module (RTC), DS3231SN FREI
  4. a 16x2 LCD module - Joy-IT 1602 I²C LCD display
(It would've been useful to give links rather than EANs — we can't click on EANs)

If the RTC module will fit the the case, most of your problems are dealt with. That one is designed to fit on (physical) pins 1, 3, 5, 7 & 9 of the main GPIO connector

The external 7" HDMI monitor I won't deal with, as it shouldn't be touching any of the GPIO.

The 1602 LCD display can require a bit of extra work: they need 5 V power to make the backlight work but (often) can work off 3.3 V logic. Like the RTC, it's an I²C device, so you'll have to use the other port and GPIO 0 and GPIO 1: see I2C at Raspberry Pi GPIO Pinout. I don't see where you'll need the other I²C port, as you've only listed two I²C devices.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.
Pronouns: he/him

BuddyHolly7
Posts: 3
Joined: Sat Jul 24, 2021 6:42 pm

Re: How do I combine several components to GPIO

Sun Jul 25, 2021 10:37 pm

mahjongg wrote:
Sat Jul 24, 2021 7:43 pm
Not a joke, but buy a soldering iron, and learn to solder, and you will never have a problem permanently connecting two metal wires together again.
Learning to solder is a must for every engineer. :mrgreen:
Hi mahjongg,

thanks for your warm welcome to the board as a mod.
No need to buy a soldering iron since I have three of them ... bought the first one about 20 years before the first RPI was invented ;-)

BuddyHolly7
Posts: 3
Joined: Sat Jul 24, 2021 6:42 pm

Re: How do I combine several components to GPIO

Sun Jul 25, 2021 10:38 pm

scruss wrote:
Sat Jul 24, 2021 8:21 pm
So you want to attach:
  1. the Raspberry Pi Touch Display
  2. a 7“ LCD Display - Joy-IT HDMI display
  3. a Raspberry Pi - Real-Time Clock Module (RTC), DS3231SN FREI
  4. a 16x2 LCD module - Joy-IT 1602 I²C LCD display
(It would've been useful to give links rather than EANs — we can't click on EANs)

If the RTC module will fit the the case, most of your problems are dealt with. That one is designed to fit on (physical) pins 1, 3, 5, 7 & 9 of the main GPIO connector

The external 7" HDMI monitor I won't deal with, as it shouldn't be touching any of the GPIO.

The 1602 LCD display can require a bit of extra work: they need 5 V power to make the backlight work but (often) can work off 3.3 V logic. Like the RTC, it's an I²C device, so you'll have to use the other port and GPIO 0 and GPIO 1: see I2C at Raspberry Pi GPIO Pinout. I don't see where you'll need the other I²C port, as you've only listed two I²C devices.
Hi scruss!
Thanks for your helpful answer and sorry for posting the EANs instead of links to the products.

The 7" display came with four separate single pole dupont connector cables which (according to the documentation) should be connected like this:
Black - display pin GND -> RPI Pin 14 (GND)
Red - display pin 5V -> RPI Pin 2 (5V)
Yellow - display pin SDA -> RPI Pin 3 (SDA)
Green - display pin SCL -> RPI Pin 5 (SCL)

This all in addition to the connection via the flex ribbon cable to the RPI display connector. I don't know why it is neccessary to connect SDA+SCL there ... maybe because of the touchscreen function?
However, since I don't need this anyway, I have now disconnected these and the display is still working fine.

So the pins 3+5 are now "free" to connect the RPI RTC (which fits into the case perfect).

It is as you said - the second display (16x2 LCD) is satisfied with 3.3V iso. 5V, too :-)

So my current connection looks like this:
PIN 01 - RPI RTC socket
PIN 02 - 5V 7" display
PIN 03 - RPI RTC socket
PIN 04 - 5V cooling fan
PIN 05 - RPI RTC socket
PIN 06 - GND cooling fan
PIN 07 - RPI RTC socket
PIN 09 - RPI RTC socket
PIN 14 - GND 7" display
PIN 17 - 3.3V 16x2 LCD display
PIN 20 - GND 16x2 LCD display
PIN 27 - SDA 16x2 LCD display
PIN 28 - SCL 16x2 LCD display

Since I just came back from work and it is past midnight now, I will try if I get a message sent to the 2nd LCD display, tomorrow.
Again thanks for your answer and time!

Return to “Beginners”