ArduCAM + Bluetooth Module = Wireless Image System

Introduction

In this demonstration we will illustrate how to transfer image wireless over Bluetooth with Arduino boards. To complete this demo we need an ArduCAM shield, a OV2640 Camera module, an Arduino UNO board or a Mega2560R3 board, and a Bluetooth TTL transceiver module.

Bluetooth is a kind of short range communication technology with high speed baud and widely used in audio and compressed video applications. BTM-5 Bluetooth module implements a PPP protocol once connected with Bluetooth master, it will be emulated as a serial port. Then we can send and receive data just like though a standard serial port.

BT1

Set the BTM-5 Bluetooth module

Before this demo user should to set the BTM-5 as a slave module, set the correct baud rate as 115200bps and paired with Notepad. User guide of BTM-5 module can be found from here.

Do the connection

The connection between BTM-5 module and Arduino board lists as follows. The Figure1 show the UNO board connection and Figure 2 show the Mega 2560 R3 board connection.

Arduino Uno bard only as one hardware serial port located in pin D0(RXD) and D1(TXD), but the D0~D7 are occupied by ArudCAM shield data bus. So we have to use software serial library to connect the free IO as UART with BTM-5 module. In the ArduCAM shield there are two IOs which are 3.3V alias of Uno pin D8(TXD) and D9(RXD).

Figure1
BT0

Arduino Mega 2560 R3 as 4 hardware serial port, D0 and D1 in serial0 are used by ArduCAM shield data bus. We can use serial1 pin 18(TXD) and 19(RXD) to be connected to BTM-5 module RX and TX pins.

Figure2

Load the sketch

In order to transfer a image as quick as we can, we have to use compress image to minimize the baud width. The Table 1 show the time required to transfer image over 115200bps baud rate with different resolution and format.

Table1

Resolution Image data size Time required to transfer with 115.2kbps
BMP 320×240 150KByte 13s
JPEG 320×240 3~6KByte 0.3~0.5s
JPEG 640×480 20~30KByte 1.7~2.6s
JPEG 1600×1200 ~130KByte ~11s

OV2640 camera module has embedded JPEG compress engine, so we have to configure the module to output JPEG image.

Arduino Uno board demo sketch download from here.

Arduino Mega 2560 R3 board demo sketch download from here.

 Send capture command and receive image data

When all the connection is done, power up the Arduino board and wait few seconds for the green LED is ON which means the pair is successfully. Then open the Hyper-terminal software or something like that to send and receive data. Or you can use the Windows demo software ArduCAM-BT.exe to give a quick try. ArdCAM-BT software can be downloaded from here.

BT2

ArduCAM-BT software receive image data, playback on the dialog box and save the each image to a JPG file.


 

 

 

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