The TX_CTRL signal is a 2.8V signal for TX Burst indication .
Refer to the following table for the status of the TX_CTRL signal depending on the embedded module state.
The TX burst indication signal, TX_CTRL, can be used to drive a LED through a transistor. It will then be a good visual indicator for any TX activities.
This green LED indicates the power supply state of UART1.
The interface can be used when it is lit depending on which power supply is present (J600 or J604) .
Refer to section 4.1 Power Supplies for more information .