RTLPlayground/doc/devices/2G5F4_10G2_V1.01.md

hongyavision HYWS-SGT0204S

RTL8372-based 4×2.5G + 2×SFP+ unmanaged switch.

Also marked on the PCB as 2G5F4_10G2_V1.01.

Stock firmware runs a factory test console on UART at 9600 baud 8N1 (banner RTL8371B start, prompt RTL8371B:). There is no management CLI and no Web interface.

Using SPI clamp in-board is the only method for initial installation and update. Erase the whole chip and verify the write (flashrom -v) before powering the board, so an incomplete write is caught before the board is powered up.

Stock flash chip is 512 KB (Bright Moon T25S40, 4 Mbit, SOP-8), which the RTLPlayground image fills exactly.

Label specifications

Case, top / front / nameplate:

• Manufacturer: hongyavision (Shenzhen Hongyavision Electronic Technology Co., Ltd.)
• Model: HYWS-SGT0204S — the nameplate is printed in Chinese and reads "10/100/1000/2500M fibre switch" and "4x 2.5G copper port + 2x 10G SFP+ optical port"
• Ports:
  • 4 × RJ45: 10/100/1000/2500 Mbps
  • 2 × SFP+: 1G / 2.5G / 10G
• Power: 12 V DC, 2 A
• Serial number: S/N-YYYYMMDDNNNN, e.g. S/N-202312010028

The top of the case only carries generic printing ("2.5G+10G High Speed Fiber Transceiver / 4-Port 2.5G Ethernet Switch+10G Fiber"), so the nameplate on the bottom is what identifies the device.

What works

• All four 2.5GBASE-T RJ45 ports at 10/100/1000/2500 Mbps
• Both SFP+ ports supporting 1G, 2.5G and 10G modules
• Copper LEDs: white (2.5G) and blue (link/activity)
• SFP LEDs: one single LED per port (link/activity)
• SFP EEPROM and DDM readable on both cages, verified with a 10G module (Rate: 0x67, module identity and DDM values via the sfp console command)
• Serial console at 115200 8N1 (RTLPlayground) / 9600 8N1 (stock)

Not verified

• The reset button footprint is unpopulated and the case has no opening for it, so it could not be tested.

PCB overview

Board markings

• Top silkscreen: 2G5F4_10G2_V1.01

Key components

• Main switch: RTL8372 (RTL8371B family), reported as RTL8372 (non-N) by RTLPlayground. The chip sits under a heatsink and its package marking is not readable.
• U1: SPI NOR flash, Bright Moon T25S40, 4 Mbit / 512 KB, SOP-8
• A 3-hole reset button footprint is present but unpopulated, and the case has no opening for it, so there is no usable reset button

Top side:

Bottom:

The stock flash chip, Bright Moon T25S40 (SOP-8, 4 Mbit / 512 KB):

Port layout

Front panel position	Logical port	Physical port	Type
SFP left	8	5	SFP+
RJ45 1	4	1	Copper
RJ45 2	5	2	Copper
RJ45 3	6	3	Copper
RJ45 4	7	4	Copper
SFP right	3	6	SFP+

Copper ports 1–4 match the KP-9000-6XH-X2 (2M-PCB43-V1.1) layout, which this board is a sibling of. The two SFP+ cages are wired the other way round compared to that board: physical port 5 is on SDS1 and physical port 6 is on SDS0.

Serial console

The board has three through-holes used as the serial console, next to the heatsink in the middle of the board and visible in the top side photo above (the silkscreen labels are printed rotated by 90°). The silkscreen labels are wrong: they are shifted relative to the actual signals.

Silkscreen label	Actual signal
TX	GND
RX	TX
GND	RX

Wiring (following the measured signals, not the labels):

USB-TTL adapter	Board pad
GND	pad labelled TX
RX	pad labelled RX
TX	pad labelled GND

• Settings: 115200 baud / 8N1 / 3.3V TTL (RTLPlayground), 9600 baud for the stock firmware
• The stock firmware only prints a few bytes and a factory test menu (?, rst, f, r, 10, 100, g1, sd, eye, …); it is not an interactive management console

LED configuration

Case silkscreen, below the RJ45 ports:

White : 2.5G    Blue : 1000M/2500M L/A

The front panel also carries a PWR LED and one LED per SFP cage (SFP1, SFP2) on the right hand side.

Port	LED	Linked, idle	With traffic
Copper	white	2.5G only	same
Copper	blue	solid	blinks (L/A)
SFP	single LED	solid	blinks (L/A)

Measured LED-ID mapping (from the RTL837x LED set registers):

LED-ID	Function
LED-ID0	copper blue LED
LED-ID1	copper white LED
LED-ID2	SFP single LED

Important: RTL837X_REG_LED_GLB_IO_EN bit 6 must be set in machine_custom_init(). Without it the RTL837x "solid" conditions (LINK/speed) do not drive the LEDs at all and only ACT does, which makes the white LED glow faintly at non-2.5G speeds.

SFP GPIO assignments

SFP	pin_detect (ModAbs)	pin_los	SerDes	I2C SDA	I2C SCL
Left (logical 8, physical 5)	GPIO30_ACL_BIT3_EN	GPIO37	SDS1	GPIO39_I2C_SDA4	GPIO40_I2C_SCL3_MDC1
Right (logical 3, physical 6)	GPIO50_I2C_SCL2_UART1_TX	GPIO10_LED10	SDS0	GPIO41_I2C_SDA3_MDIO1	GPIO40_I2C_SCL3_MDC1

pin_tx_disable is GPIO_NA on both ports. Both I2C buses are confirmed working: with the same 10G module inserted, the sfp console command reads its vendor and model from the left cage (Slot 1) and from the right cage (Slot 2), DDM values included. The insertion also shows which SerDes drives each cage - the left cage reports sds_config sds: 01 and the right cage sds: 00, which matches the table above.

Machine target

Build for this device with make MACHINE=2G5F4_10G2_V1_01, which selects the machine/2G5F4_10G2_V1_01.c board definition. It is derived from machine/KP_9000_6XHML_X2.c with the SFP cage order and the reset pin changed. The fitted T25S40 cannot be read in DIO mode on this board: an image that leaves DIO enabled does not come up at all, both at the default read clock divider of 4 and at 8 (two boards tested), while the same image with single-IO boots and runs normally. The board definition therefore sets flash_sio, which makes flash_init() use CMD_FREAD at divider 8. Only the management plane is slower, the ASIC keeps forwarding in hardware.