Automotive Module Series
AG525R-GL QuecOpen
Hardware Design
AG525R-GL_QuecOpen_Hardware_Design 54 / 104
To ensure signal integrity of USB data lines, components R1, R2 and L1 must be placed close to the
module, and also these resistors should be placed close to each other. The capacitors C1 and C2 should
be placed near the module. The capacitors C3 and C4 should be placed near the AP. The extra stubs of
trace must be as short as possible.
The following principles of USB interface should be complied with, so as to meet USB 2.0 and USB 3.0
specifications.
It is important to route the USB 2.0 and 3.0 signal traces as differential pairs with ground surrounded.
The impedance of USB differential trace is 90
Ω
.
For USB 2.0 signal traces, the trace length should be less than 120 mm, and the differential data pair
matching should be less than 0.7 mm (5 ps).
For USB 3.0 signal traces, the maximum length of each differential data pair (Tx/Rx) is recommended
to be less than 100 mm, and each differential data pair matching should be less than 0.7 mm (5 ps).
Do not route signal traces under crystals, oscillators, magnetic devices, PCIe and RF signal traces. It
is important to route the USB differential traces in inner-layer with ground shielding on not only upper
and lower layers but also right and left sides.
If a USB connector is used, please keep the ESD protection components as close to the USB
connector as possible. Pay attention to the influence of junction capacitance of ESD protection
components on USB data lines. Typically, the capacitance value should be less than 2.0 pF for USB
2.0, and less than 0.4 pF for USB 3.0.
1. USB 2.0 and USB 3.0 share the same controller, therefore they cannot be used simultaneously.
2. “*” means under development.
3.11. UART Interfaces
The module provides three UART interfaces: UART1, BT UART and debug UART.
UART1 and BT UART support RTS and CTS hardware flow control, and are used for data
transmission with peripherals.
UART1 and BT UART support 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800 and
921600 bps baud rates, and the default is 115200 bps.
The debug UART interface supports 115200 bps baud rate, and is used for Linux console and log
output.
NOTES