M4 Expansion Boards
The M4 board has an Expansion board header on the bottom side that offers options to directly expand M4 by attaching expansion boards.
The following functions are available on the M4 expansion headers dy default:
- Vcom (switched main 1S battery supply, max 4.5V)
- 2.85V (v1boards) or 3.3V (V2 boards) digital supply
- GND and DGND
- UART for wireless telemetry
- SPI (shared with onboard radio on V2 and forward)
- 4 PWM lines
If you turn the M4 board over so that the USB port points forward and the expansion board headers is pointing up, you will have the following pinout (Pin 1 on each of the 2 female headers is marked with a small arrow):
External PWM lines M5 to M8 is on the following pins:
J2.7; PB6 = M5
J2.6, PB7 = M6
J2.10,PC6 = M7
J1.10; PC7 = M8
The male connector needed to design your own expansion boards is a 2*5 pin 0.05″ pitch male header – shown below in a SMT version. Reference part number is FTSH-105-01-L-DV-TR-ND, but other similar 0.05″ headers can be used – Surface mount or Trough hole.
Header placements, board dimensions and mounting hole patterns is shown below:
You can download a diptrace board file and schematic from our FTP server and use that as a basis for creating your own expansion boards.
Expansion Board Examples
Kisssys expansion board: Micro-SD, UART (connected to a BT module), 4 PWM and 3.3v pololu stepup for powering peripherals.
Expansion Board by aBUGSworstnightmare
More info in this forum thread
Tested and flown with KISS ESC by joebar.rc
Read more about it in the M4 forum
DIY motor driving board for a brushed Octo by JussiH:
More expansion boards are in production.
A standard expansion board for using the M4 in small PWM based quads is in progress and will be offered soon. This board will contain:
- UART Serial port and BT module footprint for wireless telemetry
- 4 PWM servo Connectors
- 5 and 3.3V supplies
- Voltage divider for input voltage measuring (V2 board only)
- CAN signal distribution
- Up to 4S or 8S supply
So an Autoquad M4 with the right expander will make able to create a small brushless quad with full autonomous capabilities. And if using ESC32 with CAN bus, you can use M4 to fly a heavy payload craft with up to 16 motors AND still have 4 servo PWM channels to control Gimbal and camera functions with.
For a full featured Autoquad flight control solution with power and signal distribution, current measuring, OSD and up to 12 PWM servo channels, we have a AQ Motherboard in internal testing at the moment.
This board connects to the M4 via CAN bus and adds a lot of new functions like a 2-channel OSD, power and signal distribution, Opto-isolated camera power supply, Xbee socket, UARTs and LED drivers. The motherboard is still in internal team testing, but we expect to release it to the public in early 2015.