Data Sheet

Smart Machine Smart Decision
SIM800F_Hardware Design_V1.00 30 2015-07-31
 Serial port supports the following baud rates:
1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200bps
 The default setting is auto baud detection
Auto baud detection allows SIM800F to detect the baud rate of the host device automatically. Pay more attention
to the following requirements:
 Synchronization between DTE and DCE:
When DCE powers on with auto baud detection enabled, firstly, users must send character “A” or “a” to
synchronize the baud rate. It is recommended to send “AT” until DTE receives the “OK” response, which
means DTE and DCE are correctly synchronized. For more information please refer to the AT command
“AT+IPR”.
 Restrictions of auto baud detection:
The DTE serial port must be set at 8 data bits, no parity bit and 1 stop bit.
The URC such as "RDY", "+CFUN: 1" and "+CPIN: READY” will not be reported.
Note: User can use AT command “AT+IPR=x” to set a fixed baud rate and the setting will be saved to non-volatile flash memory
automatically. After the configuration is set as fixed baud rate, the URC such as "RDY", "+CFUN: 1" and "+CPIN: READY”
will be reported when SIM800F is powered on.
4.6.2 Serial Port Connection
The following figure shows the connection between module side (DCE) and customer side (DTE).
Figure 20: Connection of the serial interfaces
If the voltage level of UART is 3.3V at customer side, the following reference circuits are recommended for lower
cost. If the voltage is 3.0V, please change the resistors in the following figure from 5.6K to 14K.