Smart Module Series
SC200K_Series_Hardware_Design 45 / 105
To ensure USB performance, please follow the following principles while designing USB interface.
⚫
Route the USB signal traces as differential pairs with total grounding. The impedance of USB
differential traces
is 90 Ω.
⚫
ESD protection devices should be reserved at USB interfaces. Typically, the parasitic capacitance of
ESD protection devices should be less than 2 pF for USB 2.0.
⚫
Do not route USB signal traces under oscillators, magnetic devices and RF signal traces. Route the
USB differential traces in inner-layer and surround the traces with ground on that layer and with
ground planes above and below.
⚫
Layout routing requirements: keep differential signal traces of USB 2.0 of the same length, and make
sure the trace length difference of USB 2.0 does not exceed 0.7 mm.
Table 11: USB Trace Length Inside Module
4.2. UART Interfaces
The module provides three UART interfaces.
⚫
UART0: four-wire UART interface, supports hardware flow control, transmission rate up to 3.0 Mbps.
⚫
Debug UART: two-wire UART interface, used for debugging only.
⚫
UART2: two-wire UART interface.
The pin definition of the UART interfaces is shown below.
Pin No.
Pin Name
Length (mm)
Length Difference (mm)
13
USB1_DM
13.51
0.45
14
USB1_DP
13.06
174
USB2_DM
17.15
0.45
173
USB2_DP
16.70