Arduino SoftwareSerial connection with LinkSprite Jpeg Camera - arduino

Question

So we're having trouble connecting the Arduino Uno to the LinkSprite camera, we've been using the LinkSprite sample code with a few print statements added
#include < SoftwareSerial.h >
/* Linksprite */
byte incomingbyte;
SoftwareSerial mySerial(4, 5); //Configure pin 4 and 5 as soft serial port
long a = 0x0000, j = 0, k = 0, count = 0; //Read Starting address
uint8_t MH, ML;
boolean EndFlag = 0;
void SendResetCmd();
void SendTakePhotoCmd();
void SendReadDataCmd();
void StopTakePhotoCmd();
void setup() {
Serial.begin(38400);
mySerial.begin(38400);
Serial.print("Serial began\n");
}
void loop() {
SendResetCmd();
Serial.print("Reset Command Sent\n");
Serial.print(mySerial.available());
Serial.print("\n");
while (mySerial.available() > 0) {
incomingbyte = mySerial.read();
Serial.print(incomingbyte, HEX);
} //After reset, wait 2-3 second to send take picture command
Serial.print("Delay Ended\n");
SendTakePhotoCmd();
Serial.print("Take Photo Command Sent\n");
while (mySerial.available() > 0) {
Serial.print("Checking Available Bytes\n");
incomingbyte = mySerial.read();
}
byte a[32];
Serial.print("Byte array intialized\n");
while (!EndFlag) {
Serial.print("Entering While loop\n");
j = 0;
k = 0;
count = 0;
SendReadDataCmd();
Serial.print("Read Command Sent\n");
delay(250);
Serial.print("Delay Ended\n");
Serial.print(mySerial.available());
Serial.print("\n");
while (mySerial.available() > 0) {
incomingbyte = mySerial.read();
Serial.print("Incoming Byte Read\n");
k++;
if ((k > 5) && (j < 32) && (!EndFlag)) {
Serial.print("Byte Added to Array\n");
a[j] = incomingbyte;
if ((a[j - 1] == 0xFF) && (a[j] == 0xD9)) { //Check if the picture is over
Serial.print("End Flag");
EndFlag = 1;
}
j++;
count++;
}
}
for (j = 0; j < count; j++) {
if (a[j] < 0x10)
Serial.print("0");
Serial.print("Picture Printing\n");
Serial.print(a[j], HEX);
Serial.print(" ");
} //Send jpeg picture over the serial port
Serial.println();
delay(10000);
}
Serial.print("Picture Complete");
while (1);
}
//Send Reset command
void SendResetCmd() {
mySerial.write(0x56);
mySerial.write(byte(0x00));
mySerial.write(0x26);
mySerial.write(byte(0x00));
}
//void SetImageSizeCmd()
//{
//mySerial.write(0x56);
//mySerial.write(byte(0x00));
//mySerial.write(0x31);
//mySerial.write(0x05);
//mySerial.write(0x04);
//mySerial.write(0x01);
//mySerial.write(byte(0x00));
//mySerial.write(0x19);
//mySerial.write(0x22);
//}
//void SetBaudRateCmd()
//{
//mySerial.write(0x56);
//mySerial.write(byte(0x00));
//mySerial.write(0x24);
//mySerial.write(0x03);
//mySerial.write(0x01);
//mySerial.write(0xAE);
//mySerial.write(0xC8);
//
//}
//Send take picture command
void SendTakePhotoCmd() {
mySerial.write(0x56);
mySerial.write(byte(0x00));
mySerial.write(0x36);
mySerial.write(0x01);
mySerial.write(byte(0x00));
}
//Read data
void SendReadDataCmd() {
MH = a / 0x100;
ML = a % 0x100;
mySerial.write(0x56);
mySerial.write(byte(0x00));
mySerial.write(0x32);
mySerial.write(0x0c);
mySerial.write(byte(0x00));
mySerial.write(0x0a);
mySerial.write(byte(0x00));
mySerial.write(byte(0x00));
mySerial.write(MH);
mySerial.write(ML);
mySerial.write(byte(0x00));
mySerial.write(byte(0x00));
mySerial.write(byte(0x00));
mySerial.write(0x20);
mySerial.write(byte(0x00));
mySerial.write(0x0a);
a += 0x20; //address increases 32£¬set according to buffer size
}
void StopTakePhotoCmd() {
mySerial.write(0x56);
mySerial.write(byte(0x00));
mySerial.write(0x36);
mySerial.write(0x01);
mySerial.write(0x03);
}
`
The code basically sends a take picture command to the camera and then reads the HEX values that the camera sends and saves the values in an array. We know the camera works because we tested it on another device.
The problem initially was, the values that we were getting from the camera aren't correct. The EndFlag in the while loop is never toggled because the HEX values that indicate the end of a JPEG values (FF and D9) are never read so it never breaks from the while loop. Now, the terminal doesn't print anything until the camera is disconnected, then all the values seem to get flushed to the screen and the command mySerial.available() returns 0 meaning that there is nothing in the serial read buffer.

Answer 1

I compared your code with the example sketch provided from the manufacturer and figured out that your initialization procedure differs from the original. In the official sample code they first connect to the camera on 115200 serial baudrate, tells camera to change it's baudrate to 38400 and then they connect to camera again but with different speed - 38400 baud.
In your code I see that you are connecting on 38400 baud speed in the beginning. However, the camera is operating at a different speed and this explains why you get garbage instead of valid data. I recommend that you perform the correct initialization procedure, as described in the example:
void setup()
{
Serial.begin(38400);
mySerial.begin(115200);
delay(100);
SendResetCmd();
delay(2000);
SetBaudRateCmd(0x2A);
delay(500);
mySerial.begin(38400);
delay(100);
Serial.println("initialization done.");
}
Also, uncomment SetBaudRateCmd() function as it's used in the initialization procedure.