RTLPlayground/doc/devices/SWTG024AS.md

SWTG024AS

SWTG024AS has at least 4 variants that look the same.

Variants are managed and a unmanaged version. But both have pcb version v1.0 and v2.0. Also the RJ45 connectors can be all plastic/non-shielded or with metal shielding.

Brands

Brand	Type	Managed	PCB	PCB Label	Flash	Chip RTL
LIANGUO	SWTG024AS	No	SWTG024AS-v2.0	CM-23-11-2336 023-17453	512kB	8272
Haraco	ZX-SWTG124AS	Yes	SWTG024AS-v2.0	???	???	8272
Xikestore	SKS3200M-4GPY2XF	Yes	SWTG024AS-v1.0	CM-23-08-2043 023-16721	???	8272

SWTG024AS-v2.0 managed vs unmanged

Changes I found with my own board vs Managed version of the PCB.

Bottom

• R105: Installed, goes to R10-PullDown SFP2 -> TX DISABLE
• R85: Not Installed (Connected to K1)
• R90: Not installed (PowerLed)
• LED3: Not installed (PowerLed)

Top

• K1: Not installed (Reset butten)
• R95: Installed (SFP2 signal RX-LOS), mean that the manage version can use RX-LOS function.
• R270: Installed (SFP1 signal RX-LOS)
• R268: Installed (SFP2 signal TX_DISABLE, but R262 200R pull-down is to high to drive by the SOC, needs mod!)
• U5: Flash is only 512kB instead of 2/4 MBit.

Notes

• TX Disable-SFP2 and Button K1 share the same GPIO pin via R105 and R85. But with R88, TX Disable-SFP2 can be mapped to C4.
• TX Disable pull-down resistos on both SFP are to low to drive by the SOC. We need to make a Best-BOM variant so we can use all the featues.

Connectors

J4 SFP1 PINs	Signal	Component	GPIO	Notes
2	TX_FAULT	B-R262	---
3	TX_DISABLE	B-R263, T-R268	C6	R262 = Pull-down 200R
4	MODDEF2 – SDA	B-R261	C7
5	MODDEF1 – SCL	B-R260, T-R267	---
6	MODDEF0 – PRESENT	B-R259, T-R296	B30
7	RATE SEL	B-R257	---
8	LOS	B-R258, T-R270	C5
9	TO?	B-R256	---

J2 SFP2 PINs	Signal	Component	GPIO	Notes
2	TX_FAULT	B-R70	---
3	TX_DISABLE	B-R10, T-R88-L	C22	R10 = Pull-down 200R
4	MODDEF2 – SDA	B-R26	C9
5	MODDEF1 – SCL	B-R15, T-R87	---
6	MODDEF0 – PRESENT	B-R14, T-R89	C18
7	RATE SEL	B-R12	---
8	LOS	B-R13, T-R95	C19
9	TO?	B-R11	---

Note: component numbering <L>-<REFDES>-<SIDE>

• L: Layer, T=Top, B=Bottom
• REFDEES: full silkscreen like R123
• SIDE: Side of the component. when the rj45 are facing towards you are you can read the silkscreen normal. L = Left, R=right, B=bottom, T=top or P with a pin number.

T3

This connector seems to go to U4 and U10. I thing is used to connect a external CPU to controlle the SOC. Even to program the flash via the SOC. Signals are based on that U4 is likely a I2C-EEPROM, U10 is likely other SPI-chip.

T3 pin	what	Signal
1	U4-P6, 33R U10-P6	I2C-SCL, SPI-CLK
2	GND	---
3	U4-P5, U10-P5	I2C-SDA, SPI-DI/DO
4	VCC
5	33R -> U10-P2	SPI-DO/D1
6	U10-P1	SPI-CS

T8

T8 pin	what	Signal
1	C14
2	GND
3	C16
4	3V3
5	C15
6	C17

Reset ciruit

Cmp	Function
R78	33k PullUp
D3	Discharge Diode
C187	RC-Delay

Reset-line found at T-D3-D active-low.

Power supply

Board has two supply rails. 0.95 and 3.3 volt.

0.95 Core Voltage.

Voltage is made by a Richtek RT8120A Buck converter. 0.95V must be within 3%.

3.3 Voltage

Voltage is crated by a TMI3244T Buck converter. 3.3V must be within 4.5%. Chip can deliver up to 4A and the sweetspot is at 1A. So higher power SFP-modules should work.