» S

M4 Connectors & LEDs

M4 v1 (Beta Boards r4&r5) Layout

M4_TOP_900px_callout_leds   M4_BTM_900px_push-button

M4 v2 (Production Boards r6) Layout Differences

Red_Top_callout1920   Red_Btm_callout1920

Switching the Board on/off

After connecting the M4 to a 1S LiPo you can switch the board on/off via the small push button, located between arm 2 and the GPS module (see reference image above).


When using a USB connection, the M4 turns on automatically. Don’t attempt to fly on USB power alone!

Status LEDs

In total there are 6 LEDs on the M4: 2x red, 2x green, 1x blue and 1x yellow

RED LED (main power) on the corner between arm 1&4, next to the CAN connector and Micro USB
off = no power
solid = power supplied

RED LED (charging) between arm 1 and Micro USB
off = no charging, normal operation
solid = lipo charging through USB

GREEN LED (main status) on the corner between arm 2&3, next to the boot button
off = not working, boot failure
1Hz blinking = booted, disarmed mode
5Hz Blinking = disarmed, logging to SD-card
solid = armed, active

GREEN LED (onboard Deltang receiver on M4v1 beta boards) between arm 1&2, next to the radio antenna and Deltang receiver chip, needs to be activated in the parameters
off = not activated, not bound, not working
flickering = bind mode, waiting for transmitter to bind
solid = bound, connected, normal operation
Note: On the M4v2 production board the bind process will be indicated by the YELLOW LED.

BLUE LED (GPS) on the corner between arm 1&2
off = no GPS data, no 3D fix, not working
dimmed flicker = GPS working, aquiring satellites
solid = GPS 3D fix (Hacc <3m)

YELLOW LED (debug) on the corner between arm 3&4
off = no operation, not working
dimmed flicker = generally working, no data
blinking = operating, reading/writing data
Note: On the M4v2 the yellow LED indicates radio operations. Fast yellow flashing means “Binding Mode”. Solid means “Connected”.

There are several blink codes involving 2 main LEDS (blue and green) except for the red one which can only display on/off status:

TARE (leveling the copter via stick commands)
the LEDs will flash simultaniously until you release the sticks

Onboard Magnetic Calibration (calibrating the onboard compass)
the LEDs will flash rapidly, then blink slower until they go solid for a second and then show normal state.

SAVE to EEPROM (saving calibration data)
same as TARE

Please refer to the page describing the Onboard Calibration functions.


When the lipo has reached stage 2 of the lipo alarm, green and yellow LEDs will flicker simultaneously to signal a critical condition of the power supply. You can adjust it to your needs: set low level stage 1 to 3.5V and stage 2 to 3.3V. Depends on your lipo.
Bring the copter down as soon as level 2 alarm kicks in!


SWD Header Pinout

Direct access to motor ports 1 through 4 (advanced use)

If you are not using the onboard brushed motor ESCs, and are very handy with a soldering iron, you can tap into the motor 1-4 outputs directly.  For example to connect a brushless ESC or to use AQ signaling features.  Here are a couple pictures showing where to pick up the signal from.


This page was created on 8-Aug-14 by kinderkram. Last modified on 12-Nov-16 by MaxP.