Connector.md

These are notes written up about the XG Mobile connector which is found on the Asus ROG Ally as well as some ROG Flow models. The goal is to build a custom eGPU enclosure that is compatible with the XG Mobile connector.

XG Mobile Cable

The XG Mobile Cable comes with ROG XG Mobile and can be purchased from a parts store for $129 USD. It has a male XG Mobile Connector on one end and three cables on the other end: two 40-pin FPC cables and a 8-pin connector. The cable carries a USB-C connection, PCIe x8 signal pairs, PCIe clock, an SMBus/I2C connection, and some sideband signals for power detection and hot-plug support.

XG Mobile Connector

The pinout can be obtained from the GV301QC schematic (page 69).

Pin	Name	Pin	Name
C1	PCIENB_TXP0_C	D1	PCIENB_TXP5_C
C2	PCIENB_TXN0_C	D2	PCIENB_TXN5_C
C3	GND12	D3	GND21
C4	PCIENB_RXP0_C	D4	PCIENB_RXP5_C
C5	PCIENB_RXN0_C	D5	PCIENB_RXN5_C
C6	GND11	D6	GND20
C7	PCIENB_TXP1_C	D7	PCIENB_TXP6_C
C8	PCIENB_TXN1_C	D8	PCIENB_TXN6_C
C9	GND10	D9	GND19
C10	PCIENB_RXP1_C	D10	PCIENB_RXP6_C
C11	PCIENB_RXN1_C	D11	PCIENB_RXN6_C
C12	GND9	D12	GND18
C13	PCIENB_TXP2_C	D13	PCIENB_TXP7_C
C14	PCIENB_TXN2_C	D14	PCIENB_TXN7_C
C15	GND8	D15	GND17
C16	PCIENB_RXP2_C	D16	PCIENB_RXP7_C
C17	PCIENB_RXN2_C	D17	PCIENB_RXN7_C
C18	GND7	D18	GND16
C19	PCIENB_TXP3_C	D19	GPU_PCIE_CLKP
C20	PCIENB_TXN3_C	D20	GPU_PCIE_CLKN
C21	GND6	D21	GND15
C22	PCIENB_RXP3_C	D22	Reserve_NB
C23	PCIENB_RXN3_C	D23	CON_SW1_DET_NB
C24	GND5	D24	AGPU_SMB1_CLK
C25	PCIENB_TXP4_C	D25	AGPU_SMB1_DAT
C26	PCIENB_TXN4_C	D26	EC_ACGPU_MCU_IRQ#
C27	GND4	D27	P_AC_LOSS_10
C28	PCIENB_RXP4_C	D28	DGPU_PWROK
C29	PCIENB_RXN4_C	D29	GPU_RST#
C30	GND3	D30	DGPU_PWR_EN#
C31	CON_DET_TOWER#	D31	CON_DET_NB
A1	GND2	B12	GND14
A2	TX1+	B11	RX1+
A3	TX1-	B10	RX1-
A4	VBUS2	B9	VBUS4
A5	CC1	B8	SBU2
A6	D+1	B7	D-2
A7	D-1	B6	D+2
A8	SBU1	B5	CC2
A9	VBUS1	B4	VBUS3
A10	RX2-	B3	TX2-
A11	RX2+	B2	TX2+
A12	GND1	B1	GND13

40-pin connectors

Each 40-pin cable is terminated into a CABLINE-VS connector. The official Asus part number for this connector is 12017-00180600 and can be purchased from the parts store (usually with a mislabeled part number) such as here.

Note that signal names are with respect to the host meaning that TX means host transmitter and RX means host receiver. In order of the longer cable first, the pinout for the two connectors are as follows:

Pin	Connector	Description
1	D8	PCIENB_TXN6_C
2	D7	PCIENB_TXP6_C
3	GND
4	D5	PCIENB_RXN5_C
5	D4	PCIENB_RXP5_C
6	GND
7	D2	PCIENB_TXN5_C
8	D1	PCIENB_TXP5_C
9	GND
10	C29	PCIENB_RXN4_C
11	C28	PCIENB_RXP4_C
12	GND
13	C26	PCIENB_TXN4_C
14	C25	PCIENB_TXP4_C
15	GND
16	C23	PCIENB_RXN3_C
17	C22	PCIENB_RXP3_C
18	GND
19	C20	PCIENB_TXN3_C
20	C19	PCIENB_TXP3_C
21	GND
22	C17	PCIENB_RXN2_C
23	C16	PCIENB_RXP2_C
24	GND
25	C14	PCIENB_TXN2_C
26	C13	PCIENB_TXP2_C
27	GND
28	C11	PCIENB_RXN1_C
29	C10	PCIENB_RXP1_C
30	GND
31	C8	PCIENB_TXN1_C
32	C7	PCIENB_TXP1_C
33	GND
34	C5	PCIENB_RXN0_C
35	C4	PCIENB_RXP0_C
36	GND
37	C2	PCIENB_TXN0_C
38	C1	PCIENB_TXP0_C
39	GND
40	C31	CON_DET_TOWER#

Pin	Connector	Description
1	N/C	3.3V to cable
2	N/C	3.3V to cable
3	N/C	3.3V to cable
4	N/C	3.3V to cable
5	N/C	Lock switch
6	N/C	White LED switch (GND = on)
7	N/C	Red LED switch (GND = on)
8	N/C	Hidden switch on side of connector
9	D23	CON_SW1_DET_NB
10	D22	Reserve_NB
11	D31	CON_DET_NB
12	D30	DGPU_PWR_EN#
13	D29	GPU_RST#
14	D28	DGPU_PWROK
15	D27	P_AC_LOSS_10
16	D26	EC_ACGPU_MCU_IRQ#
17	GND
18	D25	AGPU_SMB1_DAT
19	D24	AGPU_SMB1_CLK
20	GND
21	A7	USB D-
22	A6	USB D+
23	GND
24	B10	USB RX-
25	B11	USB RX+
26	GND
27	A3	USB TX-
28	A2	USB TX+
29	GND
30	D20	GPU_PCIE_CLKN
31	D19	GPU_PCIE_CLKP
32	GND
33	D17	PCIENB_RXN7_C
34	D16	PCIENB_RXP7_C
35	GND
36	D14	PCIENB_TXN7_C
37	D13	PCIENB_TXP7_C
38	GND
39	D11	PCIENB_RXN6_C
40	D10	PCIENB_RXP6_C

8-pin connector

This seems like a standard pin connector. The pitch is 1.50mm. Part number is 5-1775443-8.

Pin	Connector	Description
1	GND
2	GND
3	GND
4	A5	USB CC
5	?	Shorted to VBUS
6	VBUS	USB VBUS
7	VBUS	USB VBUS
8	VBUS	USB VBUS

Signals

Here's what can be learned from looking at the GV301QC schematic. The PCIe pairs are connected to a series of muxes which can be controlled by the APU to switch between the dGPU and eGPU. The USB-C is connected directly to the system's USB circuits and does not seem to be re-purposed for any alternative usage.

CON_DET_TOWER#, EC_ACGPU_MCU_IRQ#, P_AC_LOSS_10, and the SMBus goes to a IT5125VG-192 which is the EC (embedded controller) that usually handles system tasks and power management (no datasheet is available for this model).

CON_DET_TOWER# and P_AC_LOSS_10 are fed into a MOSFET circuit for some kind of power detection.

CON_SW1_DET_NB is passed to both the APU and the EC as GPIO and is likely the way that the BIOS detects a connection. CON_DET_NB is shorted to GND and indicates to the eGPU of a connection.

DGPU_PWROK, GPU_RST#, DGPU_PWR_EN# are connected to the APU as GPIOs.

Connection handshake

1. When connector is plugged in, CON_DET_TOWER# is asserted (active low) by the eGPU and the host EC detects the connection. The eGPU detects CON_DET_NB shorted to GND and knows that the host is connected. The eGPU also de-asserts P_AC_LOSS_10 (pull down) to indicate AC power is connected.
2. When the connector lock is switched on, pin 5 on the 40P connector is shorted to GND and the eGPU detects this and asserts CON_SW1_DET_NB.
3. The host requests the eGPU to be powered on by asserting DGPU_PWR_EN# (active low) and GPU_RST# (active low).
4. The eGPU powers on the GPU and asserts DGPU_PWROK.
5. The host de-asserts GPU_RST#.
6. At this point, the connection is established and the host beings PCIe RX detection and link training.

References

• ASUS GV301QC Schematics & Board
• XG Mobile Cable, 40-pin connector, 8-pin connector, XG Mobile connector