SIM5218E Hardware Design
Figure 12:
Interface of serial ports
Serial port
z
Port/TXD @ Client sends data to the RXD signal line of module
z
Port/RXD @ Client receives data from the TXD signal line of module
All pins of all serial ports have 8mA driver, the logic levels are described in the following table
Table 8: Logic levels of serial ports pins
Parameter
Min
Max
Unit
Logic low input
0
0.3*VDD_EXT
V
Logic high input
0.7 *VDD_EXT
V0.3
V
Logic low output
GND
0.2
V
Logic high output
VDD_EXT -0.2
VDD_EXT
V
Note: VDD_EXT=2.6V, is module internal IO reference voltage.
SIM5218E provides an AT command(AT+CSUART) to support Null modem. Null modem mode
uses two lines (RXD, TXD(GND not comprised)) to setup communication between devices. The
lines connection is shown as below.
SIM5218E_ Hardware Design_V1.06
2012.09.21
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Содержание SimCom SIM5218E
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