Power request
Source capabilities
PD flow: the source advertises PDOs, the card requests one operating point, then Accept + PS_RDY make it active. Above the contracted current limit, a fixed supply normally trips protection and removes or cycles VBUS; PPS can enter constant-current (CL) regulation instead. See the USB-PD primer below.
| PDO | Supply | Voltage | Limit | Request |
|---|---|---|---|---|
| Connect a card to load the source offers. | ||||
Diagnostics and control
Device actions
Connect to detect the available command set.
Session record
Terminal
Product-image commands
device- Read card identity and firmware request limits.
request 9000 max auto- Request a source-advertised voltage using product selection policy.
request 20000 5000 fixed- Prefer a matching fixed PDO with the requested current.
request 15000 max pps- Require PPS at an advertised in-range voltage.
caps- Refresh source-advertised PDOs, including after reconnect.
enter-epr/epr-caps/exit-epr- EPR mode controls, when supported by the source.
output-on/output-off- Set the same load request as the physical control; safety inhibits still apply.
Black-box inspection uses the compact persistence query directly.
Reading diagnostics
- Hard reset
- The direction, firmware cause, and recovery interval are shown. Output permission is cleared immediately.
- Protocol lost
- The PD session ended; the card returns to passive retry and USB may disappear if VBUS falls.
- Black box
- Shows the latest six of up to 16 RAM events. A falling VDD event commits the journal; live Hard Resets also appear in the terminal.
- RAW transport
- Exact USB CDC chunks, not CC packets. Read boundaries are arbitrary.
- Telemetry
- 20 Hz measured VBUS/current samples. Power is calculated in the browser.
Front-panel warning letters
WARN spells one Morse letter, then pauses. A dot is a quick flash and a dash a long one. If several warnings are active, each letter plays in turn. R plays three times; T plays three times, or until LOAD is pressed if the dip cut the load.
- R ·–·
- Request failed: the charger refused it and the previous contract remains, or it agreed three times without delivering the voltage and the card stays at 5 V.
- S ···
- Save unavailable: the flash page for the next settings save could not be prepared or written, so changes may not be remembered.
- T –
- Tripped: the supply dropped out and it showed. It cut the load (T stays until LOAD is pressed again), restarted the display, or ended the PD session. A brief dip the board rode through is not shown.
- F ··–·
- Fallback: earlier boots lost power while restoring the remembered setting, so this boot runs a fixed PDO, 5 V, or no USB-PD at all. Press APPLY to retry the remembered setting, or adjust with the +/− keys first. Unplugging and reconnecting also retries it in full.
During display power limiting, THERM LIM stays on, TEMP WARN blinks, and the digits drop their leading zeros. These indicate the regulator power model, not a measured board temperature. PPS CV/CL follows the source’s reported PPS status; both stay off if that status is unavailable.
USB-PD primer — PDOs, contracts, PPS, AVS, EPR and resets
Negotiation
CC1/CC2 first establish attachment and cable orientation; VBUS begins at default 5 V. The source sends Source_Capabilities, a list of PDOs. The sink requests one advertised operating point. Accept approves the request and PS_RDY says the requested rail is ready. A link-level GoodCRC only confirms that a PD packet was received—it does not approve its contents.
Capability types
Fixed PDO offers one voltage with a current ceiling. PPS is an adjustable SPR range; the sink requests voltage and current inside it. AVS is the EPR adjustable range and is commonly power-limited, so available current can fall as voltage rises. EPR is the protocol mode that exposes extended-power capabilities such as 28/36/48 V and EPR AVS.
How to read this page
Requested is what the card asks for. Contract is what the source accepted. Measured V/A comes from the card ADC and may differ because of tolerance, droop, or calibration. Above a fixed contract's current limit, source over-current protection normally removes or cycles VBUS. Under PPS, the source can instead enter CL mode and reduce voltage to hold the current limit. A Hard Reset restarts PD and can also cycle VBUS; LOAD permission is cleared for safety.