Cisco SG220 / SF220 Series

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Model	SoC	PoE	Comment
SG220-26	RTL8382M
SG220-26P	RTL8382M	✓
SG220-50	RTL8393M
SG220-50P	RTL8393M	✓
SF220-24	RTL8332M		10/100 ports only
SF220-24P	RTL8332M	✓	10/100 ports only
SF220-48	RTL8353M		10/100 ports only
SF220-48P	RTL8353M	✓	10/100 ports only

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

GPIO

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)

Environment

Present only on the SG220-26P.

FAN1: TC655 at 0x1B
FAN2: TC655 at 0x1B
TEMP1: LM75A at 0x49
TEMP2: LM75A at 0x4B

JTAG

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
      +--------+