Micro Maestro - TTL serial interface problem

I’m using a micro maestro board and I’m trying to use the TTL interface to read a maxbotix MB1200 sonar range finder via the controller TTL port to my PC.
I use the USB dual port serial setting but as I connect the sonar TX pin to Maestro RX pin the red led lits and I cannot control the servo no more.
When it happens if I try to move servo via the control center, it move to desidered position and soon backs to 0. I see a Serial signal error too in the errors pane.

It seems that the Micro Maestro boards picks the signal from serial interface and use it to control (erratically) the servos.

Please can anyone help me to properly configure the board to control servos via USB and send data from RX line to PC in the same time?

Any help will be appreciated.


Unfortunately, the Maestro uses non-inverted TTL serial, which is not compatible with the Maxbotix sonar sensors’ inverted serial format. You would need to use some kind of an inverter to connect them.

You might separately have power problems - what are you using for a power supply?


Hi Paul,
many thanks for the answer. Should I use a simple NOR port or there is a different bit displacement between an inverted and non inverted serial?
If serial communication becomes too difficult, probably I will use a channel for analog input and read the analog output from maxbotix product.
But I cannot explain why, connecting the range sensor I have a serial signal error.

For power sypply I’m using a regulated 5V supply 1Amp capable with Vin pin and PWR servo line short.


I believe the serial has the same bit pattern and is just entirely inverted.

However, I do not think that “NOR port” is a real term. Do you mean “NOR gate”? That is certainly one part that could do the inversion, though I believe you could also use a NOT, NAND, comparator, or even just a transistor and two resistors (google “transistor inverter”). There are a lot of ways to do it.


Also, your power supply is minimal, but it will probably work. The reason your servo is resetting is that you are constantly getting serial errors because of the inverted signal.