#Hardware Topology

This page summarizes the current V3 baseline. The full board-level source of truth remains docs/hardware_connection_overview.md; the site is a published reading surface.

#Current baseline

• Controller: ESP32-S3
• USB hub controller: CH335F
• Persistent configuration: M24C64@0x50
• Input power protection: TPS2490
• Input telemetry: Input INA226@0x44
• Mainboard sideband expander: Mainboard TCA6408A@0x20
• Front-panel / LCD expander: Front-panel TCA6408A@0x21
• Owner-facing ports: port1, port2, port3, port4

PCA9545A@0x70 is retained only as a compatibility naming slot. The current validation board uses direct shared I²C buses and does not rely on that mux for port addressing.

#System topology

DC IN
  └─ VIN_UNSAFE -> shunt -> TPS2490 / input gate -> VIN
                      └─ Input INA226@0x44

ESP32-S3
  ├─ Sensor I2C (GPIO8/GPIO9)
  │   ├─ Front-panel TCA6408A@0x21
  │   ├─ Input INA226@0x44
  │   ├─ Port 3 INA226@0x42 + TMP112@0x4A
  │   └─ Port 4 INA226@0x43 + TMP112@0x4B
  ├─ Hub I2C (GPIO14/GPIO13)
  │   ├─ Mainboard TCA6408A@0x20
  │   ├─ M24C64@0x50
  │   ├─ Port 1 INA226@0x40 + TMP112@0x48
  │   └─ Port 2 INA226@0x41 + TMP112@0x49
  ├─ EN1..EN4 -> Port 1..4 power gate
  ├─ ISOUSB211 V1OK <- upstream isolation status
  ├─ USB D+ / D- <-> native USB
  └─ LCD + front panel + buzzer + fan

CH335F
  ├─ PWREN1#..4# -> Mainboard TCA6408A@0x20 -> MCU
  └─ OVCUR1#..4# <- Mainboard TCA6408A@0x20 <- MCU

The key boundary is that ESP32-S3 owns power gating, telemetry, persisted configuration, and the control plane; CH335F owns USB hub data behavior and the PWREN# / OVCUR# sideband.

#Input power

Input power follows this path:

VIN_UNSAFE -> 5 mΩ shunt -> TPS2490 / input gate -> VIN
                                  └─ Input INA226@0x44

Key nets:

• IN_EN: MCU-controlled input-gate qualification.
• IN_PG: high means power-good.
• VIN_ADC: MCU ADC divider sample point.

Firmware checks input qualification during boot. If input power is unsafe, IN_CE stays closed, port initialization is skipped, and runtime tasks are not released.

Input bring-up reads in this order:

1. VIN_UNSAFE exists.
2. IN_EN allows the TPS2490 input gate.
3. IN_PG reports power-good.
4. Input INA226@0x44 reports VIN / current / power.
5. boot.summary classifies VIN as Ok, Warn, or Fatal.

Only after VIN is ready does firmware probe the front panel, fan, mainboard sideband, and four output modules.

#Four-port gating

The four outputs are controlled by MCU-driven EN1..EN4:

port.power_set drives the matching ENx. port.replug means controlled power-off and power-on; it does not promise true per-port data disconnect.

#CH335F sideband

CH335F sideband signals are connected through Mainboard TCA6408A@0x20:

• P0/P2/P4/P6 read low-active PWREN1#..4#.
• P1/P3/P5/P7 inject low-active OVCUR1#..4#.
• ISOUSB211 V1OK is read on GPIO21 and separates standalone/no-upstream from upstream-managed mode.

When V1OK=low, the product keeps independent output capability and does not shut ports off just because PWREN# is high. When V1OK=high, only ports whose PWREN# is low are allowed to output power.

Initialization releases all OVCUR# lines by writing output 0xFF, polarity 0x00, and direction 0xFF.

#Two I²C buses

#Sensor / front-panel I²C

• I2C_SDA = GPIO8
• I2C_SCL = GPIO9
• Devices: Input INA226@0x44, Front-panel TCA6408A@0x21, and port3/port4 telemetry devices.

#Hub-sideband / output I²C

• HUB_SDA = GPIO14
• HUB_SCL = GPIO13
• Devices: Mainboard TCA6408A@0x20, M24C64@0x50, and port1/port2 telemetry devices.

#Front panel and display

The front-panel expander is Front-panel TCA6408A@0x21:

• P0..P4: five-way switch, mapped to Center, Right, Down, Left, Up.
• P5 = LCD_RES
• P6 = LCD_CS

LCD signals directly connected to the MCU:

• LCD_DC = GPIO10
• LCD_MOSI = GPIO11
• LCD_SCLK = GPIO12
• LCD_BLK = GPIO15

The panel is a 160x50 LCD, the driver IC is GC9D01, and LCD_BLK is currently low-active.

Two V3 display details are easy to get wrong:

• LCD_BLK is low-active; driving it as high-active turns the backlight off.
• Display orientation uses Orientation::LandscapeSwapped, not the old Landscape mapping.

Current V3 hardware cannot hard-reset Front-panel TCA6408A@0x21 from the MCU. If bus-clear succeeds but only 0x21 does not ACK, firmware records Warn/FrontPanelOffline, continues runtime, and disables only front-panel input.

#Maintenance actions and hardware capability

#Historical boundary

The following terms are historical or migration-only and do not represent current control-plane hardware:

• SC8815 + SW2303
• PSTOP_CTL1..4
• PSTOP1..4
• historical USB-C route / two-port product abstractions

#References

• docs/hardware_connection_overview.md
• docs/ch335f_tca6408a_appnote.md
• docs/specs/pw97u-control-plane-alignment/SPEC.md
• docs/specs/j6nvw-hardware-v3-pin-assignment/SPEC.md