User Manual

Smart Machine Smart Decision
SIM7100_Hardware_Design_V1.02 2015-06-16
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 17: Reference circuit of level shift
To comply with RS-232-C protocol, the RS-232-C level shifter chip should be used to connect
SIM7100 to the RS-232-C interface, for example SP3238ECA, etc.
Note: SIM7100 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.
3.3.2 RI and DTR Behavior
The RI pin can be used as an 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
interrupt event with “AT+CRIRS” AT command.
Figure 18: RI behaviour（SMS and URC report）
Normally RI will be kept high level until a voice call, then it will output periodic rectangular wave
with 5900ms low level and 100ms high level. It will output this kind of periodic rectangular wave