User's Manual

A7608SA-H_User Manual_V1.00
2022-08-26
Smart Machine Smart Decision
The A7608SA-H UART is 1.8V voltage interface. If user’s UART application circuit is 3.3V
voltage 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.
VDD_1V8 or
External 1V8
TXB0108RGYR
3.3 V
MODULE
100nF
VCCA
VCCB
100nF
OE
GND
TXD
A1
B1
TXD_3.3V
RXD
A2
B2
RXD_3.3V
RTS
A3
B3
RTS_3.3V
CTS
A4
B4
CTS_3.3V
DTR
A5
B5
DTR_3.3V
DCD
A6
B6
DCD_3.3V
RI A7
B7
RI_3.3V
UART port
47K
A8
B8
47K
Figure 15: Reference circuit of level shift
To comply with RS-232-C protocol, the RS-232-C level shifter chip should be used to connect
A7608SA-H to the RS-232-C interface, for example SP3238ECA, etc.
Note: A7608SA-H 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 to 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
interrupted event with “AT+CRIRS” AT command.
Figure 16: RI behaviour
（
SMS and URC report
）