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 board vs Managed version of the PCB.

Bottom

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

Top

• K1: Not installed (Reset Button)
• R95: Installed (SFP2 signal RX-LOS), means that the managed-version can´t use the RX-LOS function.
• R270: Installed (SFP1 signal RX-LOS), same here as above.
• 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 via R88, TX Disable-SFP2 can be mapped to GPIO36.
• 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	GPIO38	R262 = Pull-down 200R
4	MODDEF2 – SDA	B-R261, T-R266	GPIO39
5	MODDEF1 – SCL	B-R260, T-R267	GPIO40	Shared with both SFP
6	MODDEF0 – PRESENT	B-R259, T-R296	GPIO30
7	RATE SEL	B-R257	---
8	LOS	B-R258, T-R270	GPIO37
9	TO?	B-R256	---

J2 SFP2 PINs	Signal	Component	GPIO	Notes
2	TX_FAULT	B-R70	---
3	TX_DISABLE	B-R10, B-R105-R, T-R88-L	GPIO54	R10 = Pull-down 200R
4	MODDEF2 – SDA	B-R26, T-R85	GPIO41
5	MODDEF1 – SCL	B-R15, T-R87	GPIO40	Shared with both SFP
6	MODDEF0 – PRESENT	B-R14, T-R89	GPIO50
7	RATE SEL	B-R12	---
8	LOS	B-R13, T-R95	GPIO51
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

T5, serial console

T5 pin	GPIO	Signal
1	GPIO31	U0TXD (Output)
2	GND
3	GPIO32	U0RXD (Input)
4	3V3

T8

T8 pin	what	Signal
1	GPIO46
2	GND
3	GPIO48
4	3V3
5	GPIO47
6	GPIO49

Reset ciruit

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

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

GPIO

HEX VAL.	GPIO	Component	What		GPIO	Component	What
00000001	GPIO00	T-C151T, T-R28T, T-R29T	?		GPIO32	T-R143-R	U0RXD
00000002	GPIO01	T-C152T	?		GPIO33
00000004	GPIO02	T-C153T	?		GPIO34
00000008	GPIO03	T-R33T	?		GPIO35
00000010	GPIO04	B-C155	?		GPIO36	T-R88L	Optional SFP-TX-DIS1
00000020	GPIO05	B-C156	?		GPIO37	SFP1-8, R270	SFP-LOS
00000040	GPIO06	T-C157T	?		GPIO38	SFP1-3, R268	SFP-TX-DIS1
00000080	GPIO07	T-C158T, R165	?		GPIO39	SFP1-4, R266	I2C-SDA4
00000100	GPIO08				GPIO40	SFP2-5, T-R87; SFP1-5, T-R267;	I2C-SCL
00000200	GPIO09	SFP2-LED?	LEDx2		GPIO41	SFP2-4, R85	I2C-SDA
00000400	GPIO10				GPIO42
00000800	GPIO11	SFP2-LED?	LEDx2		GPIO43
00001000	GPIO12	PORT1-LED-COMMON	LEDx2		GPIO44
00002000	GPIO13	PORT1-LED-GREEN	LEDx2		GPIO45
00004000	GPIO14	PORT1-LED-YELLOW	LEDx2		GPIO46	T8-1	?
00008000	GPIO15	PORT2-LED-COMMON	LEDx2		GPIO47	T8-5	?
00010000	GPIO16	PORT2-LED-GREEN	LEDx2		GPIO48	T8-3	?
00020000	GPIO17	PORT2-LED-YELLOW	LEDx2		GPIO49	T8-6	?
00040000	GPIO18	PORT3-LED-COMMON	LEDx2		GPIO50	SFP2-6, R89	SFP-DETECT
00080000	GPIO19	PORT3-LED-GREEN	LEDx2		GPIO51	SFP2-8, R95	SFP-LOS
00100000	GPIO20	PORT3-LED-YELLOW	LEDx2		GPIO52
00200000	GPIO21	PORT4-LED-COMMON	LEDx2		GPIO53
00400000	GPIO22	PORT4-LED-GREEN	LEDx2		GPIO54	SFP2-3, T-R105L	SFP-TX-DIS1 or via T-R85 to RESET3
00800000	GPIO23	PORT4-LED-YELLOW	LEDx2		GPIO55
01000000	GPIO24	SFP1-LED?	LEDx		GPIO56
02000000	GPIO25				GPIO57
04000000	GPIO26	SFP1-LED?	LEDx		GPIO58
08000000	GPIO27	R44L	?		GPIO59
10000000	GPIO28	LED-SYSTEM, T-R50-R		?		GPIO60
20000000	GPIO29				GPIO61
40000000	GPIO30	SFP1-6, T-R269	SFP-DETECT		GPIO62
80000000	GPIO31	T-R144-R	U0TXD		GPIO63

LEDs

NAME	COMPONENTS	GPIO
SYSTEM	T-R50-R (PU-4k2), T-R49-L, T-C185-L, B-R90	GPIO28
SFP1	T-R35-L (PU-3k9), T-R34-L, T-C179-L	?
SFP2	T-R38-T (PD-4k0)	?

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.

---

1. Only on the unmanaged verions are R10 and R268 placed. But the very low pull-down resistor R10 & R262 prevent to SOC to drive does pins. A mod is needed. ↩︎

2. LEDs are found by just plugin a RJ45 connector and see with cmd gpio the status change. But the bit pattern for port 1,2 are diffrent from port 3,4. ↩︎

3. GPIO54 is used for the reset-button. T-R85 is placed. ↩︎