Serial
After a bit of research using a logic analyzer, the following appears to be the pinout of the 6 pin UART header (JP1). Default settings are baud: 115200, 8 bit, no parity, 1 stop bit.
Pin 1 3.3 V DC Pin 2 ?? Pin 3 S_in Pin 4 ?? Pin 5 S_out Pin 6 GND
JTAG
The JTAG header is a standard EJTAG header. From Wikipedia: EJTAG 2.5 and later defines a dual row 14-pin male header (mechanical connector) with 0.1"x0.1" spacing to attach a JTAG probe. 3M part number 2414-600UB is recommended.
nTRST 1 2 GND TDI 3 4 GND TDO 5 6 GND TMS 7 8 GND TCK 9 10 GND nSRST 11 12 -key DINT 13 14 VCC
Debug mode
To jump into the debugger/boot loader, hold the reset button at startup for a short time (less than half a second?). You will get a DISH>
prompt.
HEAP: addr=800740C0 size=03F8BF40 Hello, this is CREAM for AR9130![LOADER] 'CAKE' CREAM Kernel debugger Ver 1.4.2 'HeDEB' Heap debugger Ver 1.0.0 'DISH' Debugging shell Version 2.5.0