Specifications

SIM7912&SIM7906 Hardware Design V1.02
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1. SDA and SCL need to pull up to VDD_EXT by a 2.2K resistor externally.
2. For more details about AT commands please refer to Document [1] in the appendix.
3.11 UART Interface
The module provides three UART interfaces: main UART interface, debug UART interface, and BT UART
interface. Features of these interfaces are shown as below:
 Main UART interface supports 4800bps, 9600bps, 19200bps, 38400bps, 57600bps, 115200bps
(default), 230400bps, 460800bps, 921600bps and up to 4M bps baud rates. This interface is used
for data transmission and AT command communication.
 Debug UART interface supports 115200bps baud rate. It is used for Linux console and log output.
 BT UART interface supports 115200bps baud rate. It is used for BT communication and can be
multiplexed into SPI interface*.
Table 26: Definition of UART interface
Pin name
Pin no.
I/O
Functional description
Comment
CTS
56
DO
Clear to send
1.8V power domain
Default use for AT
command.
RTS
57
DI
Request to send
TXD
60
DO
Transmit data
RXD
58
DI
Receive data
DCD
59
DO
Carrier detect
RI
61
DO
Ring indicator
DTR
62
DI
Data terminal ready
sleep mode control
DBG _TXD
137
DO
Transmit data
1.8V power domain.
Used for debug only.
DBG _RXD
136
DI
Receive data
BT_CTS
164
DO
Clear to send
Default use for BT
1.8V power domain
If unused, keep it open.
BT_ RTS
166
DI
Request to send
BT_ TXD
163
DO
Transmit data
BT_ RXD
165
DI
Receive data
BT_EN
3
DO
BT function enable control
All the UART level of module is 1.8V. If it communicates with the 3.3V serial port level, a level conversion
NOTE