See Hardware/Deucalion/Deucalion_0_1_uart.jpg


From right to left:

Black GND
Yellow above GND: +5v supply
Blue next to yellow: TXD
Green next to blue: RXD

Above mentioned four wires is all you need to update firmware in Kinetis and connect to Deucalion via UART.

Another green is another RXD for second UART, another blue is another TXD.

This is related EFI_PRINT_MESSAGES_TO_TERMINAL

Orange jumper on the left is enabling LED. The single LED on Deucalion is shared between stm32 and Kinetis.