See UDOO x86 manual page 35: Socket #4, CN 15 for Braswell (UART 1) Pin 6 Tx, Pin 8 Rx, <-- this one is the first COM port (UART 2) Pin 14 Tx, Pin 16 Rx Note this type is 1.8V ultra-LVTTL I/O. Depend on use case (true RS232 signal level, 5V TTL level, 3.3V LVTTL level), you need a (different) level shifter.
Strange - now the Udoo x86 board I have will not power up if the ttl->usb connector is hooked up to the Udoo and my laptop. This was working before (splash screen and device screen came up fine, no bootloader or OS, though), and I haven't made any changes to the wiring. The light stays amber, regardless of whether I unplug the board or try the power button. Has anyone successfully connected via the serial port UART? If so, what by what method (OS/library, client/host) and with what hardware?
Minimally, you'll need a USB-1.8V LV TTL dongle. Most of the commercial USB serial dongles are 3.3V or 5V type. You don't want to feed 3.3V to Braswell X86.
This is what I have: https://www.digikey.com/products/en?keywords=768-1070-ND Splash screen and device screen work with console redirect, or used to. No further communication occurs once the bootloader is entered. Have you successfully used the serial port UART1? What combination of software (OS, terminal, etc) did you use?
Let me correct myself - after the device screen disappears and control is passed to the bootloader, communication slows to a crawl. A screen redraw takes minutes. It can not keep up with the output from the bootloader. However, as of this morning, the board will not even boot with the cable in the USB port on my laptop.
The data sheet indicates that only model number TTL-232RGVREG1V8-WE is rated at 1.8V. Is that the TTL to USB Serial Converter you are using?
