Zyxel GS1900-48

img_gs1900-48_f_1000.jpg

The GS1900-48 is a 48 + 2-port Gigabit L2 switch with 48 gigabit ports.

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.

There is experimental hardware support for the device in OpenWRT. SFP does not work.

  • 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 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.

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)

gs1900-48-gpio-reset-crop.jpg gs1900-48-gpio-reset-bodge.jpg

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.

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

  • gs1900-48.txt
  • Last modified: 2022/04/18 17:16
  • by svanheule