Micro Maestro: sad blinking yellow LED

Hi Guys,

I did a search and found a few similar posts (like this one) but I can’t solve so asking here…

The problem: Maestro just blinks yellow light slowly, once per second. ( I guess stuck in baud auto detect mode )

I’ve seen this Pololu page which explains the yellow blinking light.

I am using an Arduino Uno and a brand new Maestro Micro (6 servo).
I am using the basic example that comes with the the PololuMaestro lib.

Wire Connections are standard:

Maestro RX to Uno 11
Maestro TX tp Uno 10
Maestro Board Gnd to Uno Gnd
Maestro Board Power to Uno +5V Out
Maestro Servo Power to 5V Power Supply
Maestro RST left floating
Standard Hobby servo on channel 0.

The arduino loads the app just fine. The code runs because I’m testing with Serial.print which shows up on serial monitor.

I’ve tried a lot of different things:

  • testing the wires and they all seem fine.
  • using a single 5V power source instead of two and get the same issue.
  • a different Maestro Micro (found an old one) and it shows same blinking yellow issue.
  • swapping rx and tx lines in case I was crazy
  • removing the power to servo, removing servo, and removing arduino rx <-> maestro tx, so only wires were arduino 5v <-> maestro vin, common ground and arduino tx <-> maestro rx.
  • using the Uno’s hardwired Serial port instead of the virtual serial ports
  • using a different Uno (I found an old one).
  • adding the reset pin into the mix. I used arduino 12 <-> maestro rst and initialized maestro with “MicroMaestro maestro(maestroSerial, 12);”.
  • calling “maestro.reset()”, which works, verified by 4 fast blinks of yellow LED. But then it falls back into slow yellow LED blinking.

None of these fixed. I’m stumped.

I only have a Mac so I’m not able to use the Windows Maestro connection software.

Thank you for any ideas!


Did you configure the Maestro settings as described in the comments of the “Basic.ino” example you linked to? As mentioned in those comments, the Maestro must be configured in the “UART, fixed baud rate” serial mode, with the baud rate set to 9600 and CRC disabled for that code to work. If you have not configured these settings yet, the easiest way would probably be to find a Windows computer so that you can run the Maestro Control Center software. We do not provide any Maestro software for Mac OS X.


Hey Brandon,

Yikes I did not do that! Thank you. I don’t have Windows computer (thankfully) so I’m curious, is it possible to change the mode by plugging the Maestro into the USB on my Mac, connecting over a a terminal emulator and sending the appropriate commands? The maestro shows up on my terminal emulator, but I don’t know which commands to send it. Has anyone made a ruby or python script to do this? If not I’d be happy to and open source it of course. ( I took a quick look and did not find it, nor did I find instructions here telling how, but possibly I missed it )

Also, once I change the config, I’m assuming that is persisted in some eeprom on the device, and I wont need to change it again?



Yes, configuration settings are stored in non-volatile memory on the Maestro, so they will persist through power cycles.

If you could find or borrow a Windows or Linux machine to do the initial configuration of the Maestro using the Maestro Configuration Utility software, that would be the easiest solution. It is not possible to configure the Maestro over a serial connection (including USB serial); it can only be done over the Maestro’s native USB interface, which we do not support on macOS.