Hardware Development Guide of Module Product
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To comply with the requirements of 3GPP and EMC authentication, it is recommended to place
(U) SIM card socket close to the (U) SIM card interface, to prevent the wiring from being too
long, which might seriously distort the waveform and thus affect the signal integrity. It is
recommended to make the grounding protection for SIM_CLK and SIM_DAT signal wiring. One
0.1uF and 33pF capacitor in parallel connection between VCC_SIM and GND, and a 33pF
bypass capacitor connected between SIM_CLK, SIM_RST and GND each can filter out the
interference by RF signals. It is recommended to cascade a 20ohm series resistance on
SIM_DAT cable. And SIM_DAT must be pulled up via a 20K ohm resistance to SIM_PWR.
4.6
USB2.0 Interface
4.6.1 Description of PINs
ZM8620 has the high-speed USB2.0 interface, which supports both the full-speed mode and the
high-speed mode. USB is connected to the system board side via the PCI-E interface, to
communicate with the processor on the system board side. Its PINs are PIN36 (USB_D-),
PIN38 (USB_D+).
4.6.2 Electric Feature
The USB interface of Module complies with the USB2.0 specifications and the electrical
characteristics.
As USB is a high-speed signal cable, pay attention to the matching of USB
resistance during the actual usage. The differential resistance is 90ohm (with a deviation of 5%).
Make sure that the signal is complete.
4.7
UART Interface
ZM8620 module provides UART serial data interfaces, which work as 2-line or 4-line interface.
The module completes serial communication and AT instruction interaction with the external via
UART interfaces. The UART ports support the programmable data size, stop bits and checksum,
and have an independent TX and RX FIFOs (512 bytes for each). For the normal UART
application, and the default baud rate is 115200bps.
4.8
Power-on/Power-off & Reset Signal
The power-on process of ZM8620 module is: Pull the POWER_ON PIN high that trig power_on
Содержание ZM8620
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