USB

The QS Computer-on-Modules, such as QSMP and QS8M, contain two separate USB 2.0 compliant interfaces. High-speed USB operates at 480 Mb/s observing some basic rules or guidelines will usually guarantee successful operation.

VBUS

The QS modules does not include a signal for supplying the 5 V VBUS power for USB. An external power management chip or discrete logic for enabling VBUS is required for the host operation. The power distribution circuit must have over-current detection capability to be compliant with the USB standard. There are no dedicated pins reserved for this in the QS standard. Use General Purpose Input/Output (GPIO) pads as OE (VBUS_EN) and OC (VBUS_OC) for the VBUS power distribution circuit. Some QS modules have pins with dedicated VBUS_EN (Output) and VBUS_OC (Input) alternate functions, e.g. QS8M pin 71 - USB1_OTG_PWR and pin 72 USB1_OTG_OC. Using these may interfere with the use other standard QS interfaces. A switch designed specifically for USB power, such as the Maxim MAX1931, or a general purpose power-distribution chip, such as Micrel’s MIC2026, can be used.

Note

The i.MX8M Nano processor has only one integrated port.

Pin Signal type I/O Requirements
43 USB_VBUS_A 5V IN Can be connected to VBUS directly
44 USB_DN_A USB I/O Route USB differential signals with 90 Ω differential impedance
45 USB_DP_A USB I/O
46 USB_VBUS_B 5V IN Can be connected to VBUS directly
47 USB_DN_B USB I/O Route USB differential signals with 90 Ω differential impedance
48 USB_DP_B USB I/O

Wiring example

USB2.0 Design Recommendations

Parameter MIN TYP MAX
Operating Speed     240 MHz
Signal Trace Length     15 cm
Differential Pair Skew     5 ps
Differential Trace Impedance 81 Ω 90 Ω 99 Ω

USB3 Super Speed

The QSXP provides a complete USB3.0 interface. To implement a USB Type-C interface (UFP, DFP, or DRP), external hardware must be added to manage the two configuration channel IOs (CC1 and CC2) as well as monitor the plug orientation and switch the single USB3 SS interface.

Route all USB differential signals with 90 Ω differential impedance.

Pin Signal Requirements
25A USB_TXN  
26A USB_TXP  
50A USB_RXN  
51A USB_RXP  

USB3 Super Speed Design Recommendations

Parameter MIN TYP MAX
Operating Speed     2.5 GHz
Signal Trace Length     10 cm
Differential Pair Skew     1 ps
RX/TX Skew     1.6 ns
Differential Trace Impedance 85 Ω 90 Ω 95 Ω

See also

Texas Instruments High-Speed Interface Layout Guidelines

QS Standard Contact Group Index

Pins Funktion Pins Funktion Pins Funktion Pins Funktion
1-4 SPI 5-10 I2C 11-14 CAN 15-18 SAI
19-35 Ethernet 36-42 SD Interface 43-48 USB 49-52 Power Supply, Reset and Boot mode
53-76 18-bit RGB Display Interface 77-78 Backlight and Display Control 53-72 Camera 79-88 MIPI DSI Display
89-96 UART 97-100 SPI 1A,75A,76A,100A PCIe 25A,26A,50A,51A USB3 Super Speed