EPD47 Demo :HC08-MIC_Test

Introduction

1.This is a Dome about testing the HC08-PDM_MIC low energy Bluetooth module.

• Install the HC08-PDM_MIC module on a LilyGo-EPD47 ink screen.
• The Bluetooth low energy module HC-08 is in the serial port transparent transmission mode, so that the ESP32 in the LilyGo-EPD47 ink screen that does not need to work temporarily enters the sleep mode, so that the loss of the battery is minimized.
• There is also a PDM microphone attached to the HC08-PDM_MIC module, which can be used for voice development, and DOME will test whether it is working properly.

Hardware preparation

1.HC08-PDM_MIC Bluetooth module

2.USB to TTL serial port module

3.LilyGo-EPD47

4.ESP32 Development board

5.Button

6.FPC 6 Pin

HC08 AT Set

1.HC08 connects USB to TTL serial port module

+-----------------------------+
HC08-----------USBtoTTL
|TX----------------------RX|
|RX----------------------TX|
|VCC-----------------3.3V|
|GND----------------GND|
+-----------------------------+

2.Send AT command to set up Bluetooth module

• AT+LED=0 //Turn off the LED,and return："OK+LED=0"
• AT+NAME = INK_047 //Change Bluetooth name,and return："OKsetNAME:INK_047"
• AT+MODE = 1 //Level 1 energy saving mode (required),and return："OK"

Hardware installation

• Install the HC08-PDM_MIC module on LilyGo-EPD47

(Warning: The power must be turned off, otherwise the ESP32 module of the screen may be burned out , At your own risk)

Upload firmware

1.LilyGo-EPD47 firmware

• Open with ArduinoIED \examples\epd47_show\epd47_show.ino
• Please select the development board"TTGO T-Watch"(Otherwise, the compilation will fail because the project occupies too much storage)
• Connect PC to LilyGo-EPD47, after selecting the correct port, you can compile and upload. After the upload is successful, wait for a while until the screen displays the following text, which means success

• When the program starts, the LilyGo-EPD47 ink screen will automatically enter the sleep mode, then the overall current will drop to 1mA or lower

2. EPS32 Development board firmware

• Open with ArduinoIED \examples\epd47_blue_waker_center\epd47_blue_waker_center.ino
• Please confirm your button pin before compiling，The button pin is 15
• Connect the PC to another piece of ESP32 to compile and upload. After the upload is successful, open the serial port to observe, press the button you set, and the following screen will appear after a while

• At this time, ESP32 sends a specific wake-up character to HC-08 through the Bluetooth serial port, so that the ESP32 in LilyGo-EPD47 can return to normal working state, and can choose to enter sleep again after completing its work normally

Test the PDM_MIC

• This test program will test whether the microphone is working properly after ESP32 wakes up
• When the screen displays：“请对麦克风吹气”, Please blow into the microphone

• When the microphone detects air pressure, ESP32 enters the sleep state, waiting to be activated again

Demo video

https://github.com/Cai1902126141/LilyGo-EPD47/blob/main/DemoVideo.mp4?raw=true

Supplementary note

• Be sure to cut off the power of the HC-08 module for any plug-in operation!!!
• The HC-08 module must be set to the first-level energy-saving mode, otherwise the program cannot sleep, please ensure that the AT command is set successfully