Block Diagram¶
Below is a block diagram of the full system as well as a connection schedule. Head over to the Build-Up section for Pi header pin-out that I used and Full BOM for an exhaustive list of off the shelf components that were used.
| Tag | Source | Destination | Protocol | Purpose | Notes |
|---|---|---|---|---|---|
| 1 | Raspi 4B GPIO Header | UPS HAT E | GPIO Header (Power + I2C) | Pogo-pin header connection. Carries both the 5V power delivery and I2C battery telemetry on the same physical link | — |
| 2 | Raspi 4B (USB 3.0) | USB Internal Hub | USB 3.0 -> 2.0 | Pi's upstream link to the internal powered hub | 3.0 Hub relegated to 2.0 speeds through cable modifications |
| 3 | UPS HAT E - USB Type-A Port | USB Internal Hub | Power (5V) | Regulated output powering the hub directly, rather than drawing through the Pi's own USB power budget | Cable Stack: 90 Degree USB Type-A Adapter -> Type-A Power Pigtail -> Male to Female Dupont Connector -> Solder to Back of Hub |
| 4 | Wall via USB-C Power Supply | UPS HAT E Type-C Charge Port | Power (USB-C) | Wall/PD charging input | — |
| 5 | Raspi 4B (HDMI-1-A) | 1024×600 Display | HDMI | Video output | Cable Stack: 90 Degree Micro HDMI to HDMI -> HDMI Female to Micro HDMI Female Adapter -> Micro HDMI to 90 Degree HDMI -> Display In |
| 6 | USB Internal Hub | 1024×600 Display | Power (5V, USB) | Display power input. | Cable stack: USB-Type A Power -> Micro USB -> Display Power In |
| 7 | Raspi 4B (USB 3.0) | SSD | USB 3.0/SATA | Boot drive | Via USB -> SATA cable |
| 8 | Raspi 4B (USB 2.0) | Speakers | USB 2.0 | Audio output | — |
| 9 | Raspi 4B (USB 2.0) | Mouse | USB 2.0 | Input device | — |
| 10 | USB Internal Hub | WWAN Modem | USB 2.0 | Cellular modem data | Utilized a 90 degree to female adapter for this device |
| 11 | USB Internal Hub | USB 2.0 Hub | USB 2.0 | Front panel I/O | — |
| 12 | USB Internal Hub | Keyboard | USB 2.0 | Input device | — |
| 13 | Raspi 4B GPIO Header | OLED | I2C | Status display (shared I2C bus with the UPS HAT) | Utilized pre-terminated male/female dupont connectors and cut/solder to length |
| 14 | Raspi 4B GPIO Header | Momentary Switch | GPIO | Wake-from-halt button | Utilized pre-terminated male/female dupont connectors and cut/solder to length |
| 15 | Raspi 4B GPIO Header | FAN | GPIO | Fan on/off control | Utilized pre-terminated male/female dupont connectors and cut/solder to length |
| 16 | Raspi 4B GPIO Header | RS232 Module | UART | Serial console TX/RX | Utilized pre-terminated male/female dupont connectors and cut/solder to length |