Hardware connection
Via serial interface, the Module may communicate with MCU of 3.3V or 5V power: TD (pin 2 of
P1) connects with RXD (receiving pin of MCU), RD (pin 3 of P1) connects with TXD (transferring
pin of MCU). Should the upper computer (PC) be in RS-232 mode, please add level converting
circuit, like MAX232, between the Module and PC.
Serial communication protocol
The mode is semiduplex asychronism serial communication. And the default baud rate is 57600bps.
User may set the baud rate in 9600
～
115200bps
。
Transferring frame format is 10 bit: the low-level starting bit, 8-bit data with the LSB first, and an
ending bit. There is no check bit.
Reset time
At power on, it takes about 500ms for initialization. During this period, the Module can’t accept
commands for upper computer.
Electrical paramenter (All electrical level takes GND as reference)
Power supply
Parameter
Item
Min Typ Max
Unit Note
Power Voltage (Vin)
3.6
6.0
V
Normal working value.
Maximum Voltage
(Vin
max)
－
0.3 7.0 V
Exceeding the Maximum rating
may cause permant harm to the
Module.
Operation Current
(Icc)
90
100
110
mA
Peak Current (Ipeak)
150
mA
TD
（
output, TTL logic level
）
Parameter
Item Condition
Min Typ Max
Unit Note
V
OL
I
OL
=
－
4mA
0.4
V
Logic
0
V
OH
I
OH
= 4mA
2.4
3.3
V Logic
1
RD
（
input, TTL logic level
）
Parameter
Item Condition
Min Typ
Max
Unit Note
V
IL
0.6
V
Loigc
0
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Summary of Contents for R303A Series
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