Data Sheet

Smart Machine Smart Decision
SIM800F_Hardware Design_V1.00 42 2015-07-31
4.12.1 RF_SYNC/JD
RF synchronization signal could indicate the incoming GSM burst. The timing is shown as below:
Figure 38: RF_SYNC signal during transmit burst
GPIO11 can also be used to indicate the RF jamming. The RF_SYNC function and RF Jamming Detection
function can be switched by AT+SJDR command. For more details, please refer to document
[1]
.
Table 22: GPIO11 Multiplexing function
Note:
1. Do not pull up GPIO11.
2. This function is not supported in the standard firmware. If you need, please contact SIMCom.
4.12.2 UART2_RXD/TXD
For details, please refer to chapter 4.6.
Table 23: Pin definition of UART2_RXD/TXD
4.13 I2C BUS
The SIM800F provides an I2C interface, which supports the master role and conforms to the I2C specification.
The features of I2C interface are listed as below:
 Compliant master mode operation
 Adjustable clock speed for F/S mode operation
 Support 7-bit/10-bit addressing
Pin Name Pin Number Mode 0(default) Mode 1 Mode 2
GPIO11 67 GPIO RF_SYNC JD (RF jamming detection)
Pin Name Pin Number Mode 0(default) Mode 1
GPIO10 51 GPIO UART2_RXD
GPIO12 68 GPIO UART2_TXD