Heat, airflow & power.
Use explicit assumptions for preliminary comparisons. Start with the measured thermal evidence before interpreting these results.
Closed, nominal R07 assembly only. Moving parts in the 3D view does not update this model. These are sizing calculations, not CFD, circuit validation or a print release.
Actual Pi readings and manufacturer sources ↗. These inputs are not a calibrated enclosure model.
Enclosure temperature
| Cooling scenario | Air °C | Flow CFM | Rise °C |
|---|
Pi internal cooler recirculates air; it is not counted as an enclosure exhaust fan. The proposed fan has no selected part, mount or measured pressure curve. Double exhaust area is a comparison, not a change to the CAD.
Cooling inputs
Fan assumptions · only applied to case-fan scenario
A simple parabolic fan curve is intersected with vent resistance. Enter a real fan’s curve endpoints when selected; duct loss and recirculation need calibration.
CPU prediction withdrawn
The old fixed cooling resistance was unmeasured. No CPU or battery temperature is predicted here.
Electrical budget
| Component | Avg W | Peak W | Powered by | Heat % |
|---|
The Pi12W stress scenario uses an approximate manufacturer workload reference, not a fixed TDP or universal peak. Other entries remain unmeasured planning assumptions; consult the evidence register. Audio includes the amplifier and both speakers—do not add speaker nameplate watts again. Heat % is the fraction dissipated inside.
“Auxiliary” means a separately regulated, rated supply or proper powered USB hub. It does not make a chosen battery suitable. No power system, hub or printer has been selected.
Power & runtime inputs
Pi supply cable voltage drop
Two copper conductors at 20°C, entered contact resistance and a constant-power Pi branch. Not ampacity, USB negotiation or transient validation. The pictured cable’s gauge and connector resistance are unknown.
Electrical connection map
Read from WalterOS’s local example configuration. The heart is still disabled in that example; this is not a live Pi wiring check. No software or physical wiring was changed.
Existing interfaces
| Device | Connection |
|---|---|
| Main display | Micro-HDMI picture + USB touch / power |
| Both ear speakers | USB audio adapter → left / right driver |
| Microphone / radar | USB data + power; hub may be needed |
| Camera | Pi 5 compatible CSI ribbon |
| Pi cooler | Dedicated fan header; shared current budget |
| Future IMU / body touch | Reserve I²C GPIO2 / 3; boards and addresses undecided |
Small-display signal allocation
| Signal | Third-eye | Heart · planned |
|---|---|---|
| DIN / MOSI | GPIO10 / pin 19 | GPIO10 / pin 19 |
| CLK / SCLK | GPIO11 / pin 23 | GPIO11 / pin 23 |
| CS | GPIO8 / pin 24 | GPIO7 / pin 26 |
| DC | GPIO25 / pin 22 | GPIO24 / pin 18 |
| RST | GPIO27 / pin 13 | GPIO23 / pin 16 |
| BL | GPIO18 / pin 12 | GPIO13 / pin 33 |
SPI clock and data are intentionally shared. Chip select, reset, DC and backlight controls are separate. The extracted allocation has no exclusive-pin conflict.
The documented auxiliary power option is 3.3 V with common ground. Header rail capacity, backlight current, board labels, deployed settings and continuity still need verification. This checks assignments only—not signal integrity, circuit protection or charging behavior. Download source-backed map ↗
What this can decide
Use this to compare changes and identify what needs measuring. The next useful evidence is actual current at bright-screen / loud-audio load, closed-case temperatures, and the selected fan and battery specifications.
Model & sources
Heat balance: input heat = wall loss + heat carried through the vents. Natural flow uses buoyancy over the 164 mm vent separation; both inlet and outlet restrict flow. The warm-up curve uses one lumped thermal mass.
Nominal slot areas: 528 mm² intake / 672 mm² exhaust. These are projected design areas, before blockage—not a measured open-area survey.
Raspberry Pi power documentation ↗
Waveshare USB audio specification ↗
Still requires real testing
Fan placement and exhaust recirculation; component and battery hotspots; boot and audio peaks; deployed GPIO / I²C / SPI wiring; cable and connector ratings; speaker feedback; tip resistance; screw access; print tolerances; and touch sensitivity.
A full CFD run needs a watertight air domain, actual heat loads and fan curves, material properties and mesh convergence. An unvalidated airflow diagnostic exists; full coupled thermal, FEA, electrical protection and battery charging validation remain incomplete.