eWDT

This is a revision of my 4s WDT model to now suit Umikot V2, a new housing same electronics.

Electronic Parts (1x);

• RP2040-Plus by Waveshare
• 500mA fuse (1A would be better, some servo motors may blow 500mA fuse if stalled)
• 5V Relay (needs to switch on from esp32 output, ie; 3.3V)
• MT3608 Adj. DC-DC boost (adjusted to 5.7V)
• 1200mAh Lithium battery, check physical size
• Momentary switch
• EF90D 360 Servo
• Red LED (low battery indicator)
• Blue LED (running, use any colour)
• 270 Ohm Resistor (220 is ok, I like to run them cooler)
• 6K8 Ohm Resistor
• 10K Ohm Resistor

Other Parts

• Optional  - alternate Umikot V2 upper mech and base.
• 12 Needles for included mech, or 9 for original v2 mech (see the Umikot instructions)
• 3x M3 8mm screws to attach the housing to ring (I use countersunk but flat head will do)
• 4x M3 12mm screws to attach the prop (I use countersunk but flat head will do)
• Optional - Glue - cyanoacrylate (AKA - CA, Super glue gel) or Weldon #16. My mount is held to the mech by friction, you can glue it if you prefer.
   

eWDT_FW 

To install the FW
Connect a USB to USB-C cable to your PC, hold the down boot button on the RP2040-Plus while connecting the in USB C cable and then release the button.
You should see a drive called RPI-RP2 on your PC. Copy the eWDTv3.ino.rpipico.uf2 firmware file to the RPI-RP2 drive

0r you may use one of the older FW versions

Operation

• The USB-C port will charge the battery
• The motor is disabled while connected to USB power
• The red LED will light up when the battery voltage drops below 3.2V. Lithium battery BMS usually cutout at 3.0V, so you get a little pre warning.
• The blue LED will light up while in use or while charging.

Optional 
eWDTv3.ino.rpipico.uf2 FW has the option of 4 run times

See wiring diagram for jumper options, you may wire a switch if you want to switch between run times.