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SIM7000 _Hardware Design _V1.00 2017-05-23
The SIM7000 UART is 1.8V voltage interface. If user’s UART application circuit is 3.3V voltage
interface, the level shifter circuits should be used for voltage matching. The TXB0108RGYR
provided by Texas Instruments is recommended. The following figure shows the voltage matching
reference design.
Figure 15: Reference circuit of level shift
To comply with RS-232-C protocol, the RS-232-C level shifter chip should be used to connect
SIM7000 to the RS-232-C interface, for example SP3238ECA, etc.
Note: SIM7000 supports the following baud rates: 300, 600, 1200, 2400, 4800, 9600, 19200,
38400, 57600, 115200, 230400, 460800, 921600, 3200000, 3686400, 4000000bps. The default
band rate is 115200bps.
The RI pin description:
The RI pin can be used to interrupt output signal to inform the host controller such as application
CPU.
Normally RI will keep high level until certain conditions such as receiving SMS, or a URC report
coming, and then it will change to low level. It will stay low until the host controller clears the
interrupted event with “AT+CRIRS” AT command.
Figure 16: RI behaviour（SMS and URC report）
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