forum.excito.org

Just a bit curious to what the following jumpers and stuff are:
Or if there is anything else that could be of interest, other than the J2 serial hack.

Hi,

J2 is the serial port
J3 is the JTAG port, for debugging of the ARM core
J5-J8 are unused GPIO (general purpose I/O)
J13 is a jumper that can be used instead of R53 (nearby). If this signal is left open, the flash is disabled and the ARM's internal boot loader starts (for instance allowing reprogramming the FLASH). Just used for debug.
U2 is a USB power control IC, replaced in later revisions with a 750 mA fuse (F2, nearby).
U14 is a mont option for smaller serial flash, also used in early revisions. Now, U6 is used.
"?" (R82 etc.) are also not used GPIO.

Other stuff of interest may be I2C or SPI, both available on the board? Both are common simple hardware interfaces, for instance for connecting temperature probes and other low-speed devices. I2C is available on the RTC chip (covered by tape on your image, just below and left from the excito X logo). SPI is available on the serial flash (for instance on U14 pads).