SIM5218E Hardware Design
Figure 13:
Null modem mode of serial ports
If serial port is used in Null Modem, the pin “RI” can be used as an interrupt pin. Normally it will
stay high but in certain condition such as SMS receiving, incoming voice (CSD, video) call or
URC reported. The pin “RI” will be set low to inform the master, and it will stay low until the
master clear this interrupt with AT command(AT+CRIRS).If using seven lines to setup
communication between devices, the pin “RI” is different. First it stays high, when a voice(CSD)
call coming, the pin “RI” is set to low for about 5900ms, then it is set high again about 100ms.
The situation will repeat until that the call is answered or hung up. After the call is answered or
hung up, the pin “RI” is set high.
As DCD and DTR are not used in current serial interface, so we endue the alternate functions to
these two pin.
Functions of serial port supporting on SIM5218E is as following:
z
Standard/Null Modem mode on Serial Port Interface.
z
Contains Data lines TXD and RXD, State lines RTS and CTS
z
Serial Port can be used for CSD, PS service and send AT command for controlling module.
z
Serial Port is a high-speed port. It supports the communication rate as following:
300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600,
3200000,3686400, 4000000
Default band rate is 115200bps, and Data bits=8, Parity=None, Stop bits=1, Flow
control=None.
NOTE:
1
If user need to use a speed higher than 115200, user should consider the length of rs232
line and the speed support on user’s RS232 port.
2
The line RI behaves the same as the standard when using standard mode, but in null mode
its action is not standard which is depicted above.
Default setting in HyperTerminal software is as the following figure.
SIM5218E_ Hardware Design_V1.06
2012.09.21
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Содержание SimCom SIM5218E
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