Cisco SG220 / SF220 Series

All models share the same firmware image. The image format is the same as the bix format, used by the Zyxel GS1900 series switches.

The SG220-26 and SG220-26P appear to use the same board, although some components related to the PoE management are missing on the SG220-26's main board

• RTL8382M
• 2× RTL8218B PHYs
• RTL8214FC SFP PHY
• RTL8231 GPIO expander
  • 1× MIIM mode (virtual MIIM, address 31)
  • 2× Shift register mode (LED_CLK, LED_DAT)
• Winbond W631GU8MB (128MiB DDR3 SDRAM)
• Macronix MX25L25635F, Winbond 25Q256FVFG (32MiB SPI flash)
• Sipex SP3232, ADM3202 RS-232 transceiver

• Internal GPIO:
  • gpio1: active low, SoC reset
  • gpio2: MDC line to RTL8231
  • gpio3: MDIO line to RTL8231
• RTL8231 @ phy address 31:
  • gpio0-4: device ID
  • gpio5-6: device hardware revision
  • gpio27: reset button
  • gpio16: watchdog state (active low)
  • gpio34: (unknown, maybe watchdog related, initialised to 1)
  • gpio9: watchdog feed (10s)
  • gpio24: SFP25 "OE" (MOD_DEF0?, used to detect module)
  • gpio11: SFP25 loss of signal (used to detect media change)/
  • gpio17: SFP25 transmit disable
  • gpio28: SFP26 "OE" (MOD_DEF0?)
  • gpio12: SFP26 loss of signal
  • gpio18: SFP26 transmit disable
  • gpio15: SCK for SFP25, SFP26, TERM1, TERM2, FAN1, FAN2 (shared I2C clock)
  • SDA lines:
    • gpio13: SFP25
    • gpio14: SFP26
    • gpio29: TERM1, TERM2 (26P only)
    • gpio31: FAN1 (26P only)
    • gpio33: FAN2 (26P only)

All LEDs are controlled by the port LED peripheral:

• Ports 1-24: Green Link/Act LED (idx 0), amber PoE LED (idx 1) (26P only)
• Ports 25-26: Green Link/Act LED (idx 0), green gigabit LED (idx 1)
• Green status LED: user controlled LED for port 27, index 1
• Amber status LED: user controlled LED for port 28, index 1

The green and amber device status LEDs are wired in anti-parallel, and only one can be enabled at a time.

Present only on the SG220-26P.

• FAN1: TC655 at 0x1B. Does not appear to be present on SG220-26P.
• FAN2: TC655 at 0x1B. The TC655 controls both fans behind the PSU of the SG220-26P.
• TEMP1: LM75A at 0x49
• TEMP2: LM75A at 0x4B

The JTAG header uses the MIPS eJTAG pin-out, with pin 12 (key) bound to ground.

• J4.1 TRST#: 1k pull-down
• J4.3 TDI: 10k pull-up
• J4.7 TMS: 10k pull-up
• J4.9 TCK: 10k pull-up
• J4.11 SRST#: 10k pull-up

      +-J4-----+
TRST# |  1   2 | GND
  TDI |  3   4 | GND
  TDO |  5   6 | GND
  TMS |  7   8 | GND
  TCK |  9  10 | GND
SRST# | 11  12 | GND
  N/C | 13  14 | VCC
      +--------+

• Product page
• Series firmware download page
• GPL source code