Worklog Hypothetical Pi Portable

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
for a while now, i've been interested in building a raspberry pi portable but I might not be able to depending on the price of parts, hence the name "hypothetical pi portable".

i do have a question before i start compiling a BOM and planning my build.

i’m planning on using a raspberry pi 4 and desoldering/removing usb and ethernet to slim the board down. from my understanding, usb has 4 connections: vcc, ground, data-, and data+. if i remove the usb ports, will there be 4 solder pads/ terminals i can connect to?
sorry for the noob question, i don't have too much experience with raspberry pis.
 
Last edited:
Joined
Apr 27, 2018
Messages
160
Likes
68
Location
Kentucky
Portables
Wii Laptop V2.0, GameCube SPITE
for a while now, i've been interested in building a raspberry pi portable but I might not be able to depending on the price of parts, hence the name "hypothetical pi portable".

i do have a question before i start compiling a BOM and planning my build.

i’m planning on using a raspberry pi 4 and desoldering/removing usb and ethernet to slim the board down. from my understanding, usb has 4 connections: vcc, ground, data-, and data+. if i remove the usb ports, will there be 4 solder pads/ terminals i can connect to?
sorry for the noob question, i don't have too much experience with raspberry pis.
Yes and no. The regular USB 2.0 ports have 4 pins, so removing it will leave you with 4 pads to solder to. The RP4 also has a USB 3.0 port, and those have 9 pins instead of 4 because they have faster data transfer.
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
Yes and no. The regular USB 2.0 ports have 4 pins, so removing it will leave you with 4 pads to solder to. The RP4 also has a USB 3.0 port, and those have 9 pins instead of 4 because they have faster data transfer.
ah, got it. i don’t think i’ll be needing the usb 3.0 ports so i think i should be fine.

EDIT: how would i go about removing the usb, ethernet, and hdmi? i’ve looked it up, and some say to desolder the ports, while others say to cut using a dremel or other tools.
 
Last edited:
Joined
Apr 27, 2018
Messages
160
Likes
68
Location
Kentucky
Portables
Wii Laptop V2.0, GameCube SPITE
ah, got it. i don’t think i’ll be needing the usb 3.0 ports so i think i should be fine.

EDIT: how would i go about removing the usb, ethernet, and hdmi? i’ve looked it up, and some say to desolder the ports, while others say to cut using a dremel or other tools.
If you aren’t planning in using them, you could remove them via dremel but be careful not to damage the board.
I would suggest desoldering them using a Soldering iron and desoldering vacuum pump, they are really cheap on amazon. Another method is using a hot air rework station and using hot air to take it off, but you have to be careful not to blow off any components in the process. Research deSoldering with a vacuum pump and with a hot air rework station and see which would be better for you.
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
If you aren’t planning in using them, you could remove them via dremel but be careful not to damage the board.
I would suggest desoldering them using a Soldering iron and desoldering vacuum pump, they are really cheap on amazon. Another method is using a hot air rework station and using hot air to take it off, but you have to be careful not to blow off any components in the process. Research deSoldering with a vacuum pump and with a hot air rework station and see which would be better for you.
alright, i’ll probably try out using a desoldering pump.
 

Dmcke5

.
2020 1st Place Winner
Joined
Feb 16, 2020
Messages
216
Likes
883
Location
Queensland, Australia
Portables
3
For what it's worth, I really struggled getting some of the ports off the pi 3 I did. The ground plane on the PCB must be massive because it just kept sucking the heat out of my soldering iron. I ended up attacking mine with a Dremel carefully to break the tabs that hold the ports into the board. I was however able to successfully de-solder the actual contacts to ensure they were useable when I was done.
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
For what it's worth, I really struggled getting some of the ports off the pi 3 I did. The ground plane on the PCB must be massive because it just kept sucking the heat out of my soldering iron. I ended up attacking mine with a Dremel carefully to break the tabs that hold the ports into the board. I was however able to successfully de-solder the actual contacts to ensure they were useable when I was done.
alright i'll keep that in mind, i might have to buy a dremel.

on another note, i've started messing around with fusion360 to start designing my case. @Dmcke5, in your switch lite sized pi portable worklog, i saw that the 3d model of your case had models of your arduino, pi, and other components. how did you go about adding these?
 

Dmcke5

.
2020 1st Place Winner
Joined
Feb 16, 2020
Messages
216
Likes
883
Location
Queensland, Australia
Portables
3
I usually download any that I can from grabcad and import them. Anything I can't find I measure and draw up myself. You need to watch it though, the model of the psp joystick I downloaded (and designed the case around) wasn't all that accurate so the mounting holes weren't in quite the right spot. I managed to drill them out a little to make it work but I do lean towards measuring my own parts where possible for that reason.
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
For what it's worth, I really struggled getting some of the ports off the pi 3 I did. The ground plane on the PCB must be massive because it just kept sucking the heat out of my soldering iron. I ended up attacking mine with a Dremel carefully to break the tabs that hold the ports into the board. I was however able to successfully de-solder the actual contacts to ensure they were useable when I was done.
i’ve done some research and it turns out that’s you can add some leaded solder onto the components so that they come off easier. the pcbs are made with lead free solder which is harder to melt. they can be removed easily after adding leaded solder.

also, @Dmcke5, in your pi portable, you soldered the hdmi connection directly to the driver board. i have nowhere near that much skill, as i’m a soldering novice. because of this, i planned on using a display serial interface LCD. i now realize that the DSI port on the pi is pretty tall and it would end up making the portable thicker. so, i’ve thought about removing the DSI connector and soldering directly to the connections. would this be too hard for a novice? i don’t want to risk losing a pi to a soldering error.
 

Dmcke5

.
2020 1st Place Winner
Joined
Feb 16, 2020
Messages
216
Likes
883
Location
Queensland, Australia
Portables
3
i’ve done some research and it turns out that’s you can add some leaded solder onto the components so that they come off easier. the pcbs are made with lead free solder which is harder to melt. they can be removed easily after adding leaded solder.

also, @Dmcke5, in your pi portable, you soldered the hdmi connection directly to the driver board. i have nowhere near that much skill, as i’m a soldering novice. because of this, i planned on using a display serial interface LCD. i now realize that the DSI port on the pi is pretty tall and it would end up making the portable thicker. so, i’ve thought about removing the DSI connector and soldering directly to the connections. would this be too hard for a novice? i don’t want to risk losing a pi to a soldering error.
The pins on the dsi connector are the same spacing as the HDMI I thought, so it's probably of a similar difficulty. And yes, I added leaded solder to help get the heat into the components but I still struggled.

As for the difficulty of soldering small things, I do have a fair bit of experience with a soldering iron. I've been soldering since I was a kid (probably about 10-11 years old when I started, 30 now) however I have a hard time stopping my hands from shaking on tiny stuff like that. If you've got nice steady hands you should be right, just tin everything first, use the smallest iron tip you can get your hands on and test for shorts before you power up and you should be fine. Biggest danger IMO with work like this is lifting a pad off the board whilst de-soldering as that will potentially stop you from being to able to use the board. A good temperature controlled soldering iron is a must, use a nice high heat and only keep it in contact with the board for a short period of time.
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
The pins on the dsi connector are the same spacing as the HDMI I thought, so it's probably of a similar difficulty. And yes, I added leaded solder to help get the heat into the components but I still struggled.

As for the difficulty of soldering small things, I do have a fair bit of experience with a soldering iron. I've been soldering since I was a kid (probably about 10-11 years old when I started, 30 now) however I have a hard time stopping my hands from shaking on tiny stuff like that. If you've got nice steady hands you should be right, just tin everything first, use the smallest iron tip you can get your hands on and test for shorts before you power up and you should be fine. Biggest danger IMO with work like this is lifting a pad off the board whilst de-soldering as that will potentially stop you from being to able to use the board. A good temperature controlled soldering iron is a must, use a nice high heat and only keep it in contact with the board for a short period of time.
thanks for your quick reply! i looked up a picture of the pi 3a+ which i believe is what you used. the hdmi is much smaller than the dsi, but i’ll still try to follow the tips you gave me. i have a weller wlc100 iron, will that be good enough? i don’t have a pencil tip or something thin like that so i’ll have to find one.
 

Dmcke5

.
2020 1st Place Winner
Joined
Feb 16, 2020
Messages
216
Likes
883
Location
Queensland, Australia
Portables
3
thanks for your quick reply! i looked up a picture of the pi 3a+ which i believe is what you used. the hdmi is much smaller than the dsi, but i’ll still try to follow the tips you gave me. i have a weller wlc100 iron, will that be good enough? i don’t have a pencil tip or something thin like that so i’ll have to find one.
I googled that iron, and it looks like a decent enough unit. Can't give you advice on where to find tips but I can tell you I used a 0.5mm tip on mine for this job. And fair enough on the dsi port, I was pretty sure the spacing on the ribbon cable was 0.5mm like the HDMI, but maybe they staggered the pins on both sides of the port to increase the spacing. Been a few months since I looked at mine so I can't remember lol
 

YveltalGriffin

First Wii U Trimmer
.
Joined
Jun 7, 2016
Messages
292
Likes
1,050
Location
South Florida
Portables
5
Using the display parallel interface on the Raspberry Pi eats up a lot of the GPIO pins, but it is much easier to solder up, removes the need for a driver board of any kind, and will be more forgiving than HDMI in terms of wire length and signal integrity. I highly recommend using it if you don't need 1080p or higher; it's nearly plug and play. I use it for mini Pi projects pretty often. You can grab a TFT Friend or something similar to power the backlight and break out the signals from the LCD. You are limited in resolution, however, probably to around 1280x720.

Old but good reference:
 

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
Using the display parallel interface on the Raspberry Pi eats up a lot of the GPIO pins, but it is much easier to solder up, removes the need for a driver board of any kind, and will be more forgiving than HDMI in terms of wire length and signal integrity. I highly recommend using it if you don't need 1080p or higher; it's nearly plug and play. I use it for mini Pi projects pretty often. You can grab a TFT Friend or something similar to power the backlight and break out the signals from the LCD. You are limited in resolution, however, probably to around 1280x720.

Old but good reference:
thank you so much for the suggestion! it seems much easier and should produce the same, if not better results at cheaper price. i’m not too concerned about the gpio, because i’m using an arduino pro micro for controls. my only worry is that the 5v and ground pins will be overpopulated, because i’m planning on powering the pi via gpio. but as i’m trying to keep the portable thin, can i connect digital pins on the pi to the TFT friend using magnet wire? i’ll be using 22awg (solid or stranded? i’m not sure) wire for 5v, ground, and 3.3v.
 

YveltalGriffin

First Wii U Trimmer
.
Joined
Jun 7, 2016
Messages
292
Likes
1,050
Location
South Florida
Portables
5
You can totally use magnet wire for the data lines. And I'd go with stranded wire for power and ground. It's more flexible, and not prone to breaking inside the insulation at the worst possible time!

Also, a classic trick is making a power distribution board out of some stripboard to give yourself more power and ground rails to solder to. I wouldn't try to solder multiple wires to a single GPIO pin, things get crowded quickly.
 

Dmcke5

.
2020 1st Place Winner
Joined
Feb 16, 2020
Messages
216
Likes
883
Location
Queensland, Australia
Portables
3
@YveltalGriffin now I wish I'd known that was possible when I started my project! This certainly isn't something that's well documented. When I looked into it I was only able to find people using the proprietary raspberry pi screen with that output. I've been considering a complete overhaul of mine so this may be something I'll have a go at. Thanks!
 

YveltalGriffin

First Wii U Trimmer
.
Joined
Jun 7, 2016
Messages
292
Likes
1,050
Location
South Florida
Portables
5
@YveltalGriffin now I wish I'd known that was possible when I started my project! This certainly isn't something that's well documented. When I looked into it I was only able to find people using the proprietary raspberry pi screen with that output. I've been considering a complete overhaul of mine so this may be something I'll have a go at. Thanks!
Happy to help! Most ARM SOCs have the capability to drive these parallel RGB LCDs directly for use in cheap tablets and whatnot. The proprietary RasPi Foundation display uses a different connection though, MIPI DSI, which is a much more advanced protocol and can drive way higher resolution panels. It's too bad the Pi's SOC isn't as open-hardware as the Allwinners and stuff, otherwise more people would be aware of the DPI interface. Anyway, now you guys know about it and can go driver-less for future Pi projects! >:)
 
Last edited:

A_s6

.
Joined
Apr 15, 2020
Messages
152
Likes
104
Location
jack frost sanctuary
Portables
i don’t give a hee ho
Happy to help! Most ARM SOCs have the capability to drive these parallel RGB LCDs directly for use in cheap tablets and whatnot. The proprietary RasPi Foundation display uses a different connection though, MIPI DSI, which is a much more advanced protocol and can drive way higher resolution panels. It's too bad the Pi's SOC isn't as open-hardware as the Allwinners and stuff, otherwise more people would be aware of the DPI interface. Anyway, now you guys know about it and can go driver-less for future Pi projects! >:)
this was a lifesaver:D!

@YveltalGriffin I've been considering a complete overhaul of mine so this may be something I'll have a go at. Thanks!
i’ll also be looking forward to this!
 
Last edited:
Top