From b5e395b825094996d1705aaaa7d7fe869761a47f Mon Sep 17 00:00:00 2001 From: Fl_GUI Date: Mon, 9 Jun 2025 00:59:02 +0200 Subject: [PATCH] describe the pi platfrom --- platform/bim.md | 35 +++++++++++++++++++++++++++++++++++ platform/graphical-stack.md | 7 +++++++ 2 files changed, 42 insertions(+) create mode 100644 platform/bim.md create mode 100644 platform/graphical-stack.md diff --git a/platform/bim.md b/platform/bim.md new file mode 100644 index 0000000..1c9897b --- /dev/null +++ b/platform/bim.md @@ -0,0 +1,35 @@ +Bill of materials: + +1) raspberry pi 3a+ +It's a smaller raspberry pi board. +I went for a soc instead of a microcontroller so that I can have easy networking, and a remote terminal. +It was also available from a local store and I like buying local. + +2) Waveshare 4.3inch capacitive touch display for Raspberry Pi, DSI Interface, 800x480 +It's the smallest DSI display I could find. +I wanted to use DSI so that I didn't need extra extra power for an HDMI display. +Using a DSI connector also has a lower footprint than using HDMI. +I really wanted to keep this project as small as possible for some reason. + +3) Adafruit USB Type C Power Delivery Dummy Breakout - I2C or Fixed - HUSB238 +From experience a raspberry pi always complains about undervoltage. +I thought that this could be fixed with USB-PD. +Except the raspberry pi 3a+ doesn't have USD-PD, let alone a usb-c port. +The Pi 4 has one, but I wanted a smaller footprint. +So I got this board to connect to the power gpio pins of the pi. +I set it to 5V-3A which is what the Pi wants at most. +Though it sometimes still complains about too little voltage. +Either my cabling has a voltage drop, or the display draws too much current. +Maybe that's why DSI displays are less common for raspberry pis. +Maybe this can be fixed by setting the voltage higher and using a buck converter to go back to 5V, but with more amps. +Ah well, the pi works just a little slower on lower voltage which is acceptable. + +4) M2.5 and M3 nuts and bolts +The raspberry pi mounts to the display with the supplied hardware, but the display mounts to the case with some longer M2.5 bolts. +The case itself is put together with M3 screws and bolt. +There are no heated inserts. +Instead I embed nuts into the print by prism shaped leaving voids in screw holes, and pausing the printer in gcode to insert a nut. +If the clearances are right the nut is secured in place while having some tolerance, and even supports the next overhang. +You should hear the nuts rattle if you shake the part. +It's pretty secure, as tightening the nut compresses the 3D printed wall that's surrounds the screw hole. +I haven't used threaded inserts before, but I already prefer this. diff --git a/platform/graphical-stack.md b/platform/graphical-stack.md new file mode 100644 index 0000000..1eaa6bf --- /dev/null +++ b/platform/graphical-stack.md @@ -0,0 +1,7 @@ +The raspberry pi image runs wayland nowadays, so I had the pleasure of figuring this out. +Next (on top?) of wayland the pi runs sddm. https://github.com/sddm/sddm/ +Sddm runs a desktop which consists of Cage running the gummi binary. https://github.com/cage-kiosk/cage +The gummi binary is an openGL 2.1 application, because that's what the pi supports. +The binary uses glfw and glad to get things working. + +I hope that by using cage I can run an another graphical application from within gummi, and later kill it. -- 2.47.1