Zyxel GS1900-48
The GS1900-48 is a 48 + 2-port Gigabit L2 switch with 48 gigabit ports.
Firmware
It ships with a bootloader based on Realtek's SDK for RTL83xx SoCs and Linux 2.6 based on Realtek's SDK. It has a web interface for all management functions.
OpenWRT Support
There is experimental hardware support for the device in OpenWRT. SFP does not work.
Hardware
- RTL8393M SoC
- Macronix MX25l12805D (16MB flash)
- 128MB RAM
- 6 × RTL8218B external PHY
- 2 × RTL8231 GPIO extenders
- One configured as shift register to control the port LEDs
- One configured in MIIM mode (phy address 0x3) for GPIO usage: reset button, SFP cages
2 Uplink ports are SFP cages which support 1000 Base-X tmini GBIC modules.
Power is supplied via a 230 volt mains connector. The board has a hard reset switch SW1, which is is not reachable from the outside. J4 provides a 12V RS232 serial connector (AT/Everex layout) which is connected through U8 to the 3.3V UART of the RTL8393. Conversion is done by U8, a SIPEX 3232EC. To connect to the UART, wires can be soldered to R603 and R602.
SDA of the left SFP cage is connected to gpio 26 of the closeby RTL8231, SCL to 24. For the right cage, SDA is GPIO30 and SCL is 31.
Board details
JTAG
The board has an unpopulated eJTAG header. The SMD resistor configuration is such that the interface is disabled by default. To be able to use the JTAG interface, the following changes need to be made:
- R171 permanently asserts nTRST. Move R171 (pull-down) to R525 (pull-up) to allow remote assertion of nTRST.
- R48 is unpopulated, leaving nSRST unconnected. (optional) Add a 0 ohm resistor to complete the connection.
- Add 2×7 pin header, or at least add connections to TDI, TDO, TCK, TMS and (one) GND pins.
With these modifications, two devices will be found in the JTAG chain:
Info : JTAG tap: auto0.tap tap/device found: 0x00001001 (mfg: 0x000 (<invalid>), part: 0x0001, ver: 0x0) Info : JTAG tap: auto1.tap tap/device found: 0x00000001 (mfg: 0x000 (<invalid>), part: 0x0000, ver: 0x0)
Hard reset circuit
Looking at the circuit around the hard reset button (SW1), one can see an RC (debouncing) circuit (R210+C32). R465 is a pull-up, to maintain the de-asserted state of the RC-circuit's output leading to the SoC (via 0-ohm R403).
U25 has marking "8AQP" and is most likely some kind of transistor. C666 buffers VCC for pad U25:4, U25:1 (large pad) is connected to GND. U25:3 connects to the SoC's reset line (R403). Pad U25:2 leads to a pull-up resistor (R464 next to U31). It is possible that this is some form of "DC OK" signal, that starts out at GND, but will switch to a high impedance on U25:3 once VCC stabilizes at the required level.
The board config reports that GPIO5 on the RTL8231 (U38) can be used to reset the SoC. GPIO5 leads to TP2 on the board, but neither are connected electrically to U25:2 or U25:3, nor to R403 next to the SoC. A bodge wire can be installed to enable runtime reset-by-GPIO.
Board configuration
GS1900# show board **************************** GS1900-48 **************************** ============================ Board GPIO ============================ Device Pin Direction Default Current ------- ---- ---------- -------- -------- INT 0 OUT 0 0 INT 1 OUT 1 1 INT 2 OUT 0 0 INT 3 OUT 0 0 INT 8 OUT 1 1 INT 9 OUT 1 1 INT 12 IN 0 0 INT 13 OUT 1 1 INT 14 OUT 1 1 INT 15 OUT 1 1 INT 16 IN 0 0 INT 17 OUT 1 1 INT 18 OUT 0 0 INT 19 IN 0 0 INT 20 OUT 1 1 INT 21 IN 0 0 INT 22 IN 0 0 INT 23 OUT 1 1 EXT 0 IN (IN ) 0 0 EXT 1 IN (IN ) 0 1 EXT 2 IN (IN ) 0 1 EXT 3 IN (IN ) 0 1 EXT 4 IN (IN ) 0 0 EXT 5 OUT (OUT ) 1 1 EXT 6 OUT (OUT ) 1 1 EXT 7 IN (IN ) 0 1 EXT 8 OUT (OUT ) 1 1 EXT 13 OUT (OUT ) 0 0 EXT 14 OUT (OUT ) 0 0 EXT 15 OUT (OUT ) 0 0 EXT 16 OUT (OUT ) 0 0 EXT 17 OUT (OUT ) 0 0 EXT 18 OUT (IN ) 0 0 EXT 22 IN (IN ) 0 1 EXT 23 OUT (OUT ) 0 0 EXT 24 OUT (OUT ) 0 1 EXT 25 OUT (OUT ) 0 1 EXT 26 IN (IN ) 0 1 EXT 27 IN (IN ) 0 1 EXT 28 IN (IN ) 0 1 EXT 29 OUT (OUT ) 0 0 EXT 30 OUT (OUT ) 0 1 EXT 31 OUT (OUT ) 0 1 EXT 32 IN (IN ) 0 1 EXT 33 IN (IN ) 0 1 EXT 34 OUT (OUT ) 1 1 ============================ Board Configuration ============================ ====== Port ================== Type Usr Phy Media Speed Duplex Attr ---------- ---- ------- ----------- -------------- -------- ------- 1000M 1 (0) 0 Copper (A) ALL Auto 0 1000M 2 (0) 1 Copper (A) ALL Auto 0 1000M 3 (0) 2 Copper (A) ALL Auto 0 1000M 4 (0) 3 Copper (A) ALL Auto 0 1000M 5 (0) 4 Copper (A) ALL Auto 0 1000M 6 (0) 5 Copper (A) ALL Auto 0 1000M 7 (0) 6 Copper (A) ALL Auto 0 1000M 8 (0) 7 Copper (A) ALL Auto 0 1000M 9 (0) 8 Copper (A) ALL Auto 0 1000M 10 (0) 9 Copper (A) ALL Auto 0 1000M 11 (0) 10 Copper (A) ALL Auto 0 1000M 12 (0) 11 Copper (A) ALL Auto 0 1000M 13 (0) 12 Copper (A) ALL Auto 0 1000M 14 (0) 13 Copper (A) ALL Auto 0 1000M 15 (0) 14 Copper (A) ALL Auto 0 1000M 16 (0) 15 Copper (A) ALL Auto 0 1000M 17 (0) 16 Copper (A) ALL Auto 0 1000M 18 (0) 17 Copper (A) ALL Auto 0 1000M 19 (0) 18 Copper (A) ALL Auto 0 1000M 20 (0) 19 Copper (A) ALL Auto 0 1000M 21 (0) 20 Copper (A) ALL Auto 0 1000M 22 (0) 21 Copper (A) ALL Auto 0 1000M 23 (0) 22 Copper (A) ALL Auto 0 1000M 24 (0) 23 Copper (A) ALL Auto 0 1000M 25 (0) 24 Copper (A) ALL Auto 0 1000M 26 (0) 25 Copper (A) ALL Auto 0 1000M 27 (0) 26 Copper (A) ALL Auto 0 1000M 28 (0) 27 Copper (A) ALL Auto 0 1000M 29 (0) 28 Copper (A) ALL Auto 0 1000M 30 (0) 29 Copper (A) ALL Auto 0 1000M 31 (0) 30 Copper (A) ALL Auto 0 1000M 32 (0) 31 Copper (A) ALL Auto 0 1000M 33 (0) 32 Copper (A) ALL Auto 0 1000M 34 (0) 33 Copper (A) ALL Auto 0 1000M 35 (0) 34 Copper (A) ALL Auto 0 1000M 36 (0) 35 Copper (A) ALL Auto 0 1000M 37 (0) 36 Copper (A) ALL Auto 0 1000M 38 (0) 37 Copper (A) ALL Auto 0 1000M 39 (0) 38 Copper (A) ALL Auto 0 1000M 40 (0) 39 Copper (A) ALL Auto 0 1000M 41 (0) 40 Copper (A) ALL Auto 0 1000M 42 (0) 41 Copper (A) ALL Auto 0 1000M 43 (0) 42 Copper (A) ALL Auto 0 1000M 44 (0) 43 Copper (A) ALL Auto 0 1000M 45 (0) 44 Copper (A) ALL Auto 0 1000M 46 (0) 45 Copper (A) ALL Auto 0 1000M 47 (0) 46 Copper (A) ALL Auto 0 1000M 48 (0) 47 Copper (A) ALL Auto 0 1000M 49 (0) 48 Fiber (A) ALL Auto 0 1000M 50 (0) 49 Fiber (A) ALL Auto 0 ====== Fiber ================= Fiber Port Number: 2 ------------ Fiber Detect LPort Present MediaChg OE Status LOS Status ------ -------- --------- ---------------------- ---------------------- 48 OE OE Enabled (GPIO:EXT_26) Enabled (GPIO:EXT_27) 49 OE OE Enabled (GPIO:EXT_32) Enabled (GPIO:EXT_33) ------------ Fiber Optical LPort SMI DEV SMI TYPE ID Delay SCK SDA ------ -------- --------- ----- ------- ------ ------ 48 SFP1 8 BITS 0x50 4000 EXT_25 EXT_24 49 SFP2 8 BITS 0x50 4000 EXT_31 EXT_30 ------------ Fiber TX Disable LPort GPIO ------ ------ 48 EXT_23 49 EXT_29 ====== Button ================ ------------ Reset Button GPIO: EXT_3 Timer: 1(sec) Action: Reboot Timer: 4(sec) Action: Restore Factory ====== Led =================== SYS (REG) ALARM (REG) ====== Reset ================= Type: GPIO GPIO: EXT_5 ====== WatchDog ============== Type: REG