SIM8905-EVB Kit_User Guide_V1.02
CD2
USIM_DET USIM card detection
4.9 UART Interfaces
The SIM8905-EVB supports 2 UART interface, J605 and J606. There is a level shifter U603 on the EVB, it converts the 1.8V digital voltage of the module to 3V, then it is converted to RS232 through U601. UART1
(J605) supports hardware flow control and the pins are pin34~pin37. UART2(J606) is a 3-line UART interface and does not support hardware flow control, the pins are Pin93 and Pin94. The Schematic of the
UART is as following:
Figure 38: Reference Design for Uart Interface
The following figure shows the pin assignment of UART port (J605/J606) . www.simcom.com 43 / 56
SIM8905-EVB Kit_User Guide_V1.02
Figure 39: Pin Assignment of UART Port (Bottom View)
Table 12: Pin Definition of UART Port
Pin No. Pin Name
I/O
Description
4
5
6
7
8
9
4
5
6
7
1
2
3
J606 (DEBUG Interface)
RS232_TXD2
RS232_RXD2
8
9
J605
1
2
3
GND
RS232_TXD1
RS232_RXD1
GND
RS232_CTS1
RS232_RTS1
I
O
I
O
I
O RS232 Transmit data
RS232 Receive data
Ground
RS232 Transmit data
RS232 Receive data
Ground
Clear To Send
Require To Send www.simcom.com 44 / 56
