peet.za.net

[PDU-12V-V3_1 0001]

Chassis

1U rackmout chassis consisting of a Fibre Patch Panel 24 port blank (with front port brackets removed) with a 1U Blank Panel welded to the front.

Front panel

• Power switch with red LED indicator.
• 200mm fuse holder fitted with 10A fuse.
• RESET switch to reset the controller.

Front panel LED indicators

• System status RGB LED:
  • Indicates error condition.
  • Normal processing condition.
  • Solid = Initialising, Blinking = Attempting to connect to WiFi network.
  
  
• Connectivity status RGB LED:
  • Unable to reach any of the external servers.
  • Normal processing condition, connected to the internet.
  • (Blinking) attempting to connect to one of the external servers.
  
  
• 2 x Bi-Color LED, seperated from the relay LED indicators, both indicating the same value due to specification change during development
• Battery voltage indicates more than 50% capacity remaining.
• Battery voltage is low, system has been shut down.


• A set of 2 Bi-Color LEDs for relay status (4 total)
  • Top row (controlled by microcontroller):
    • Relay is not activated, DC jack has output power.
    • Relay has been disabled by direct command to the controller, or due to low battery condition.
  • Bottom row (connected directly to relay using CMOS CD4009UBE Hex Buffer/Inverter:
    • Relay is not activated, DC jack will have 12V power.
    • Relay is activated, the relevent DC jack will NOT have power.

Rear of unit

• Screw terminal connector for 12V battery input.
• 4 independent female DC jacks with dust protector, providing 12V at up to 32A total.

Internal hardware

• DC-DC Buck converter 12V to 5.1V as power supply for ESP32 controller and CMOS ICs.
• ESP32 DEVKIT 1 controller (Tensilica 32-bit Dual-core Xtensa L6, 240MHz (under-clocked to 120MHz), 4MB Flash.
• Four INA219 I2C Voltage/Current/Power sensors, one for each DC jack output. Note these are also used to read the battery voltage to determine remaining charge.
• 4-channel 5V coil NO/NC 16A relay module, for power-cycling or disabling power to one or more DC Jacks.
• DIP16 CD4009UBE Hex Buffers/Inverters because I bough the wrong bi-color LEDs.

Functionality

• Power measured and available real-time on all of the 12V outputs.
• Unit connects to WiFi network (credentials previously supplied), then attempt to ping configured external servers to determine internet connectivity.
• If battery power (as measured and averaged by the 4 12V INA219 sensors) falls below pre-set value (battery low condition):
  • Grounds all relays, effectively disconnecting all output power.
  • Looking at (possibly snmp?) ups to allow devices (Windows and Debian) to shutdown properly.
  • Sets both Status LED and Connectivity status LED to RED.
  • Goes into deep-sleep mode for 15 minutes (minimal power consumption) mode, upon wake it checks if the battery level has increased (due to charging), if not repeat..

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Failures in above design:

• Have not found any yet