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FIBOCOM SC138-
NA
Series Hardware Guide
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speed differential routing.
2)
The differential impedance control is made properly, 90 Ω + - 10%, and the length difference of
differential line is controlled within 0.7 mm.
3)
The stray capacitance of ESD device must be less than 0.5 pF.
3.5
UART
SC138 module has three UART interfaces, which are all in voltage domain of 1.8 V. The pin definition is
as follows:
Table 3-8 Definition of pins of UART interfaces
Pin Name
Pin No.
I/O
Description
Remarks
DBG_UART_TX
90
DO
UART data transmission
Debug interface
DBG_UART_RX
89
DI
UART data receiving
UART_TX
45
DO
UART data transmission
-
UART_RX
46
DI
UART data receiving
-
UART_CTS/TS1_I2C_SDA 47
DI
UART clear-to-send
Can be configured
to I3C
UART_RFR/IS1_I2C_CLK
48
DO
UART request-to-send
Can be configured
to I3C
UART_TX/GPIO_8
209
DO
UART data transmission
-
UART_RX/GPIO_9
207
DI
UART data receiving
-
The voltage domain of each serial port is 1.8 V; when communicating with other voltage domain serial
ports, it is necessary to add level conversion chips. The reference circuit design is shown in the following
figure:
