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ESC Board

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IsaacWax edited this page Oct 3, 2024 · 11 revisions

ESC Board

Overview

The ESC board will be a carrier board that holds 1X of the Lumenier Mini Razor Pro 4in1 20x20 F3 BLHeli_32 45A 2-6s ESC . This will be connected to the board with castellated holes like the Seahawk II ESC carrier board except the form factor will be shifted to make it so the board will plug into the bottom on the backplane. Doing this will help improve thermal effects on the ESC as it will be sinked directly to the bottom of the electrical box.

I want to change the connectors to reduce the count possibly using board to edge connectors. Also for the connection to the thrusters, I want to have those connections run through the backplane, so the thrusters plug into the backplane instead of connecting directly to the ESC Board. This will make it easier to handle this system because basically all cabling will be connected to one board.

The other large change is the plan to add an RP2040 plus the most minimal required peripherals onto the ESC Board. This will reduce cabling and increase the response time. The Pi4/ Pi5 have 4x UART and we only need 2X / ESC board to communicate over micro ROS. For programing the the board we will either add USB or we could use a UART to serial device.

RP2040 Design Notes

  • On p.16 of the hardware design document I am confused about fig.14. It seems like this would make a 10V node if both were plugged in at the same time (we should probably add this to the board to be safe)
The 3.3V pin is an output from Raspberry Pi Pico or Raspberry Pi Pico W and should not be connected to an external
power source. It is intended to be used as an output to provide power to external circuits.
Figure 14. Section of
schematic showing
power input
The VSYS pin is the main system power supply on Raspberry Pi Pico and Raspberry Pi Pico W. From this supply, a 3.3V
supply is generated and used to power RP2040; and also the 3.3V output pin which we can use to power circuits on our
design.
The VBUS pin is connected to the VBUS of the micro USB connector. There is an onboard diode connecting VBUS to
VSYS, which means that VBUS can be used to power VSYS, but not the other way around.
This design provides different options for providing the power, and the choice of which one to use depends very much on
your application. The first thing to consider is if the USB functionality of Raspberry Pi Pico or Raspberry Pi Pico W will be
used.
3.1.1.1. Not using USB
If we are not using USB, then we must provide power for Raspberry Pi Pico or Raspberry Pi Pico W. One way of doing
this is to provide power to Raspberry Pi Pico/Raspberry Pi Pico W from our board, through Raspberry Pi Pico or Raspberry
Pi Pico W’s pins. See Figure 15 for an illustration of this. The preferred way of implementing this is to provide a voltage
to the VSYS pin via a Schottky diode (Figure 14). The one-way nature of the diode ensures we don’t encounter any
problems if we also supply power to the VBUS pin (accidentally or deliberately). Raspberry Pi Pico and Raspberry Pi Pico
W can take a voltage of between 1.8 and 5.5V, as they have an internal buck-boost regulator (one which can regulate the
output to a higher or lower voltage than its input), but due to the fact we have an additional voltage regulator in our
design (U1, more on this later), we need to make sure that VSYS is greater than 3.5V so that U1 will operate correctly.

image

Part Links

This series of connector seems like a good compromise from doing a card edge connector. It is quite low profile and runs both signal and power. 127A/inch liner or 30A/ power pin https://www.molex.com/en-us/products/part-detail/461142160

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