MEIG SLM 320 - Page 33

MeiG_SLM320_Hardware Design Manual
MeiG Smart Technology Co., Ltd
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Table 11 Description of debugging serial port pin
Pin Name I/O PIN Description
DBG_RXD I 11
Module receiving data
DBG_TXD O 12
Module send data
Table 12 Serial port logic level
Parameter Min value Max value Units
V
IL
-0.3 0.6 V
V
IH
1.2 2.0 V
V
OL
0 0.45 V
V
OH
1.35 1.8 V
The serial port level of SLM320 module is 1.8V. If the client host is 3.3V, the level shifter needs to be
added in the serial port application. TI's TXB0104PWR is recommended. The following picture is a
reference design:
VCCB
B1
GND
B2
B4
B3
B6
B7
B5
B8
VCCA
A1
OE
A2
A4
A3
A6
A7
A5
A8
Translator
0.1uF
0.1uF
VDD _EXT
VDD _MC U
RI_MC U
DCD_MC U
CTS_MC U
RTS_MC U
DTR_MCU
TXD_MCU
RXD_MC U
RI
DCD
CTS
RTS
DTR
TXD
RXD
DSR_MC U
DSR
Figure 15 Level conversion chip reference circuit