Hardware Guide

FIBOCOM MC610 Series Hardware Guide 39/71

grounding in series.

3.5.3 USIM Design Requirements

The circuit design of SIM card needs to comply with EMC standards and ESD requirements, and needs

to improve the electromagnetic susceptibility to ensure that the SIM card can work stably. The following

points should be strictly observed in the design:

⚫ The layout of SIM card slot should be close to the module as far as possible, and away from RF

antenna, DCDC power supply, clock signal line and other strong interference sources.

⚫ The SIM card slot with metal shielding shell is used to improve the electromagnetic susceptibility;

⚫ The length of route from the module to the SIM card slot should not exceed 100 mm, and too long

route will reduce the signal quality.

⚫ SIM_CLK and SIM_IO signals are isolated by ground line to avoid mutual interference. If it is difficult

to complete it, at least SIM signal needs to be used for a group of signal protection signal.

⚫ The filter capacitor and ESD device of SIM card signal line are placed close to the SIM card slot,

and the upper limit of equivalent capacitance of ESD device is 33 pF.

⚫ PCB clearance at the bottom of SIM card holder to avoid short circuit of pin to ground.

3.6 UART Interface

3.6.1 UART Interface Definition

There are four groups of serial ports in MC610 modules: main serial port UART1, downloading interface

UART2, serial port UART3 and serial port DEBUG. The main features of four serial ports are described

below:

Main serial ports UART1 and UART3 support the baud rate of 2,400 bps, 4,800 bps, 9, 600 bps,14,400

bps,19,200 bps, 28,800 bps, 33,600 bps, 38,400 bps, 57,600 bps, 115,200 bps, 230,400 bps, 460,800

bps, 921,600 bps and 1,000,000 bps. The default baud rate is 115,200 bps, which is used for data

transmission and AT command transmission. But only UART1 can continuously send the AT command to

wake up the module after the module is sleeping, and other serial ports are unavailable.

DEBUG serial port supports the baud rate of 115,200 bps, which is used for FIBOCOM internal