Measurement units: milliampere (mA) at 3.3 V bus. Instrument: Keysight U1242C DMM (mA range) in series with the OBC 3V3 rail, or USB inline ammeter on 5 V with the LDO efficiency (0.85) factored in. Scope: OBC board only (STM32F446 + sensors + radio IC). Propulsion, magnetorquer drivers, and camera are measured separately under their own power sub-files when those boards arrive at the bench.
| Mode | Description | Expected (mA) | Measured (mA) | Notes |
|---|---|---|---|---|
| Boot | Reset → first main() instruction | ≤ 80 | TBD | First 10 ms |
| Idle | FreeRTOS idle, no TX, no payload | ≤ 60 | TBD | Steady state |
| Nominal | All sensors polling at 1 Hz, beacon every 30 s | ≤ 90 | TBD | Reference state |
| Imaging | Payload camera active + compression | ≤ 180 | TBD | Bursts ≤ 5 s |
| TX | UHF radio PA on during beacon transmit | ≤ 320 | TBD | 1 s burst |
| Safe mode | Only telemetry + comm + health | ≤ 70 | TBD | Reduced duty |
| Stop | STOP mode with IWDG wake-up every 2 s | ≤ 2 | TBD | Between passes |
All “Expected” values come from the link budget + datasheet typical-current tables. Actual measurements populate the “Measured” column during HIL bench work; anything > 120 % of expected triggers a design review.
With daily orbit-average current drawn at ≤ 90 mA and solar array
output ≥ 3 W peak on UniSat OBC form factor (6 × 0.295 efficient
2 × 4 cm panels, per docs/budgets/power_budget.md), the battery SOC
should remain ≥ 50 % over a 24 h sunlit / eclipse cycle. Bench
measurement populates the left-hand side of that inequality;
on-orbit telemetry (EPS APID 0x011) populates the right-hand
side post-launch.
firmware/stm32/Core/Src/command_dispatcher.c (Phase 6
follow-up) so a ground operator can drive the OBC through
every row of the table without physical access.