LoRa_Camera_Trap

Create a remote camera trap using LoRa.

Description

This project uses LoRa to transmit an image captured by ESP32-CAM. Image is then stored on an SD card on the receiver side and displayed on a web server hosted on the receiver. Transmission time varies between 3 to 30 minutes (HD image), based on bandwidth and spread factor. Higher bandwidth means higher data rate, but shorter range. In order to achieve ideal transmission range, both sender and receiver must be in a line of sight. Only OV2640 camera module is currently supported.

Hardware requirements

1x ESP32-CAM
1x FTDI adapter for ESP32-CAM
1x DOIT DevKit V1 ESP32
2x SX1278 LoRa transceiver module (make sure you get the correct frequency band for your region)
1x SD card reader module
1x PIR motion sensor
1x I2C LCD display (optional)
some jumper wires and solder 

Pinouts:

SENDER:                                                             RECEIVER:
___________________________                                         ______________________
SX1278:           ESP32-CAM:                                        SX1278:          ESP32:
GND               GND                                               GND              GND
NSS               15                                                NSS              15
MOSI              13                                                MOSI             13
MISO              12                                                MISO             12
SCK               14                                                SCK              14
VCC               3V3                                               VCC              3V3
RST               not connected                                     RST              4
DIO0              2                                                 DIO0             2

PIR:                                                                I2C LCD:
data              3                                                 GND              GND
3V3               VCC                                               5V               VIN
GND               GND                                               SDA              21
                                                                    SCL              22
FTDI:                                                                    
GND               GND                                               SD Card reader:
5V                5V                                                GND              GND
RX                U0T(3), only connect while flashing               MISO             19
TX                U0R(1)                                            SCK              18
                                                                    MOSI             23
                                                                    CS               5
                                                                    3V3              3V3

You must attach an antenna to you LoRa modules, otherwise you are risking damage to the modules. A piece of insulated wire will do, but adjust the length to the frequency of your module. Antenna should be quarter or half a wavelength long. I have used quarter a wavelength.

Usage

First you will need to install the following libraries:

SPI.h 
SPIFFS.h 
SD.h 
LoRa.h 
WiFi.h 
LiquidCrystal_I2C.h 
ESPAsyncWebServer.h 
ESPAsyncTCP.h 
EEPROM.h 
time.h 
esp_camera.h

Receiver

Board name is DOIT ESP32 DEVKIT V1.

First, type in the WiFi credentials.

const char* ssid = "SSID";
const char* password = "password";

In case you want to create a soft access point, uncomment softAP() in setup(), and comment wifiConnect().

As a next step, change the ntp server to fit your region in setup(). First parameter is time shift in seconds.

configTime(7200, 0, "your.ntp.server");

You may want to change LoRa bandwidth and spread factor as well, which are set to 500kHz, and 7 by default. In that case, you will need to do the same changes on sender module too, otherwise you will not receive any packets! These parameters can also be configured on the webpage, where the sender will be configured automatically. More on that later.

To upload code, push the BOOT button on your board as soon as you see dots and underscores, and release it after the board starts booting. After board initialization, connect to IP address printed by the serial monitor. You should see this page: image

Values are empty, because no photo has been captured yet. In order to do so, let’s set up the sender module.

SENDER

Board name is AI THINKER ESP32-CAM.

The sender is ready without changing anything, but you may want to change picture resolution in setup(), which is HD by default. In that case, replace

config.frame_size = FRAMESIZE_HD; 

by one of the following values:

FRAMESIZE_UXGA (1600 x 1200)
FRAMESIZE_SXGA (1280 x 1024)
FRAMESIZE_XGA (1024 x 768)
FRAMESIZE_SVGA (800 x 600)
FRAMESIZE_VGA (640 x 480)
FRAMESIZE_CIF (352 x 288)
FRAMESIZE_QVGA (320 x 240)

I have not adjusted the image holder on the webpage to contain images of other resolutions than HD, so they may not be displayed correctly.

You can also change other camera settings, but I won’t go into detail on that.

In order to upload code to ESP32-CAM, connect the FTDI adapter accoring to the pinout. Then connect GPIO0 to GND, and press the reset button as soon as you see dots and underscores. After you are done, disconnect GPIO0 from GND and connect PIR module according to the pinout. Press reset button once more.

Webpage

After both devices are set up, wave your hand in front of the PIR sensor, to trigger motion detection. You should see changes on the webpage and LCD display. Image was taken and is now being transmitted. All values except image will now be automatically updated every 5 seconds. In order to update the image, refresh the page. Once the image is fully transmitted, it will stay on the screen until a new one is taken.

If you configure LoRa bandwidth or spreading factor on the webpage, changes will take effect only after a picture is fully transmitted. The reason is that all the parameter changes must be applied to both sender and receiver. This is achieved by sending a config packet from receiver to sender. The sender listens for packets only for a short time right after it has finished image transmission.

Common issues

Here are some issues I came across while working on the project:

PROBLEM                                                               SOLUTION
1. LoRa won't initialize                                              Make sure the module is connected exactly according to the pinout.
2. Reciever is not getting any packets                                Make sure both modules are configured with the exact same bandwidth, spread factor, and coding rate. Keep the RSSI above -120 dBm and SNR above 0. Also don't forget to trigger the motion sensor!
3. Pictures are too brigth                                            Move the camera out of direct sun, or take extra dummy pictures before transmitting.
4. There is no photo on the webpage, even if new packets are coming   Refresh the page. If the problem persists, it means the initial packet was not received. Restart both modules and try again. Make sure you start the receiver before the sender.
5. Pictures contain horizontal stripes and weird discoloring          Some packets were lost. Increase bandwidth, decrease sprad factor, or decrease range. 
6. Timestamp is shifted by a few hours                                Change the ntp server and adjust the time shift in configTime().

GitHub

View Github