UARTs

• Logic level (3.3V) signals
• FFUART speeds to 230 kbps (normally mapped to ttyS0 in the kernel and Y0 in some schematics )
• HWUART speeds to 921 kbps (normally mapped to ttyS3 in the kernel and Y1 in some schematics)
• Both can use RxD, TxD, RTS, CTS.
• STUART speeds to 230 kbps (normally mapped to ttyS2)
• BTUART is not an exposed interface; mapped to ttyS1 by the kernel and connected physically to the bluetooth module if one is present.

• Note! Current kernels use ttyS3 (HWUART) for bluetooth. This is available on the BTUART pins by setting GPIO42 and 43 to AF3 - and this is the default configuration. This can be very confusing if you want to use the HWUART for something else! To re-enable HWUART on ttyS3, make bluetooth use ttyS1 (see /etc/default/bluetooth) and then set GPIO42 to AF1 in and GPIO43 to AF2 out. You can then set GPIO48 to AF1 out (HWUART TXD) and GPIO49 to AF1 in (HWUART RXD).

http://docwiki.gumstix.org/Gumstix_UARTs

UARTs

FFUART

FF_CTS

FF_RTS

FF_TXD

FF_RXD

Logic level (3.3V) signals FFUART speeds to 230 kbps (normally mapped to ttyS0 in the kernel and Y0 in some schematics ) FFUART pins are located on the 60-pin Hirose connector