Used board is SimpleBCG 8bit (Unfourtunately I have not found any schematics)
Measurements have shown, that pullup current is too high on a Rx (Tx) pins on UART port.
Therefore I can not use my Arduino Due board for controlling gimbal through UART (Processor's pin pullup is max 6mA-9mA). Arduido Uno can bearely handle this (but for now it works): Atmega 328P pin pullup is 20mA.
What to do? Is it known problem? Is there some fix from schematics? I tried different firmwares „SimpleBGC 2.2 b2“ and „SimpleBGC 2.40 b7“. On both cases, I could measure current 27mA.
Well I measured that current on rx pin but arduino due can't drive so much current. You think that 1k resistor really help? For due the current should not be larger than 6mA.