User Manual

instruction to MCU. In order to reduce power consumption, LoRa and MCU are
normally in dormant state. Each of them handles its own message. When it needs
another, it will wake up another and gives AT instruction to another.
When AT instruction are sent on both side, additional course will happen when
there are at the same time. Therefore, the design for this is a “half duplex” mode.
That is: only one side can send instruction at one time. Therefore, before either
side sends instruction , it has to monitor whether the other wants to send
instruction or not. If the other side has “grabbed the right to send
information”,you have to wait until the current round of interaction is completed
before initiating.
The following is a complete process for initiating AT instruction at both ends.
4.1 The complete process of MCU initiate an interaction with the LoRa
module.
LoRa module MCU
| LoRa in dormant mode |
| <-- Check whether PE6 has been send low level signal first-- | <1>
| <--- PE7 sends low level signal (wake up MCU) ---- | <2>
| --- PE6 sends low level signal (LoRa is ready) ---> | <3>
| < --- send AT instruction ------------ | <4>
| ----- PE6 sends high level signal（restoration） ---> | <5>
| <--- （After AT）PE7 sends high level signal---- | <6>
| LoRa is working |
| |
Note ：
1. Step 1 to detect PE6, is "listen first before saying" , to ensure that "the
other party does not send it himself when sending" . If the PE6 is
already with low level signal, the other party is sending it. At this
time,wait for the other party to send again (don't go to step 2
immediately).
2. Step 2 to let the PE7 in low level signal, is actually to "seize the right to
speak" ; ---- because the other party comes to detect if the PE7 is in low
level signal before sending it.
3. Step 3, PE6 turn into low level signal in response to MCU, telling MCU
that "I have been awakened and ready for serial reception, you can
send" ;
4. Step 5 is the PE6 turn into high level signal, strictly speaking, is the
LoRa module detected the serial port is sending data and immediately
turn PE6 into high level signal (not waiting for the AT instruction be
sent finished.);
5. By step 6, a round of interaction is completed.
When the two sides send data, "seize the right to speak" .