USB

The QSCOM 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 QSCOM 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 QSCOM standard. Use General Purpose Input/Output (GPIO) pads as OE (VBUS_EN) and OC (VBUS_OC) for the VBUS power distribution circuit. Some QSCOM 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 QSCOM 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.

Signals

Pin Signal type I/O Requirements
43 USB2_VBUS 5V IN Can be connected to VBUS directly
44 USB2_DN USB I/O 90R differential pair
45 USB2_DP USB I/O
46 USB1_VBUS 5V IN Can be connected to VBUS directly
47 USB1_DN USB I/O 90R differential pair
48 USB1_DP USB I/O

Wiring example

QSCOM Standard Contact Group Index

Pins Funktion Pins Funktion Pins Funktion Pins Funktion
1-4 SPI 19-35 Ethernet 49-52 Power Supply, Reset and Boot mode 79-88 MIPI/LVDS Display Interface
5-10 I2C 36-39 SD Interface 53-76 18-bit RGB Display Interface 89-96 UART
11-14 CAN 43-48 USB 77-78 Backlight and Display Control 97-100 SPI