Collected notes on the router, it's operation, and hacks. on Sunday 09 April 2006 by mattei in Notebook > Technical hits: 8386
Serial communications
I have verified continuity on a GigaFast board with a multimeter. Using the squared connection of J1 as the first of six pins:
Board RTL8186 Symbol Description
------ ------- ---------- ------------------------------
Pin 1 Pin 51 DVDD33 CPU power +3.3V (Digital).
Pin 2 Pin 80 UCTS0PIN UART0 Clear-to-Send signal.
Pin 3 Pin 73 URTS0PIN UART0 Request-to-Send signal.
Pin 4 Pin 79 USIN0PIN UART0 In data signal.
Pin 5 Pin 58 USOUT0PIN UART0 Out data signal.
Pin 6 Pin 35 DGND33 CPU 3.3 GND (Digital).
From previous hacks on the 8181 AP boards, common wisdom says that a MAX3232 and five 0.1uf capacitors can be used to complete the serial interface. The communication settings should then be:
On the RTL8186, several settings are defined by hardware state rather than software configuration. These values are strapped from GPIO pins. To enable the JTAG interface, ANTSELPIN (Pin 147) must be high. The JTAG function is disabled by default.
Board RTL8186 Symbol Description
------- -------- ------------- -------------------------------------
Pin 1 Pin 146 GPAPIN[8] GPIO, also JTAG_TRSTN
Pin 2 various GND
Pin 3 Pin 33 GPAPIN[6] GPIO, also JTAG_TDI
Pin 4 various GND
Pin 5 Pin 116 GPAPIN[9] GPIO, also JTAG_TDO
Pin 6 various GND
Pin 7 Pin 8 GPAPIN[7] GPIO, also JTAG_TMS
Pin 8 various GND
Pin 9 Pin 144 WLLED0PIN[0] WLAN Tx/Rx indicator, also JTAG_CLK
Pin 10 various GND
Pin 11 Pin 188 GPAPIN[10] EXTERNAL RESET
Pin 12 various GND
Also of note, unused SW1 is connected to input pin GPAPIN[10] - external reset. The actual reset button on the router is connected to GPIO pin 77.
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