I have en ESP32 CAM rotated by a stepper motor  which it controls. It receives requests over a TCP socket to rotate a certain number of degrees and take a photo which it then sends back over the socket. Everything works well BUT the photo is being taken before the rotation. Here is the code that handles the client

void doMove(int targetDegrees){

targetDegrees = targetDegrees % 3600;

// convert target degrees to position, targetDegrees is degrees x 10

long target = circle*targetDegrees/3600.0+.5;
long current = stepper.currentPosition()% circle;
long positionDiff = target-current;

Serial.print(“targetDegrees: “);Serial.println(targetDegrees);
Serial.print(“target: “);Serial.println(target);
Serial.print(“current: “);Serial.println(current);
Serial.print(“positionDiff: “);Serial.println(positionDiff);

// go to the position via the shortest route
if (positionDiff> halfCircle){
positionDiff-=circle;
}
else if(positionDiff<-halfCircle){
positionDiff +=circle;
}
Serial.print(“New positionDiff: “);Serial.println(positionDiff);

stepper.move(positionDiff);
while(stepper.distanceToGo()!=0){
stepper.run();
}
Serial.println(“completed move”);
Serial.print(“current Position = “);Serial.println(stepper.currentPosition()% circle);
Serial.print(“target: “);Serial.println(target);
}

// handle client

void handleClient(WiFiClient client) {
Serial.println(“Client connected “);

Serial.println(“Receiving data…”);
std::vector<uint8_t> data;
while (true) {
size_t available = client.available();
if (available == 0) {
delay(1);
continue;
}
std::vector<uint8_t> chunk(available);
size_t read = client.read(chunk.data(), available);
if (read == 0) {
break;
}
chunk.resize(read);
data.insert(data.end(), chunk.begin(), chunk.end());
if (read < chunkSize) {
break;
}
}

if (data.size() != sizeof(int)) {
Serial.println(“Invalid request”);
return;
}

int angle = *reinterpret_cast<const int*>(data.data());
Serial.print(“Received request for angle “);
Serial.println(angle);
doMove(angle);
Serial.println(“About to take picture”);
camera_fb_t* fb = esp_camera_fb_get();
if(!fb) {
Serial.println(“Camera capture failed”);
return;
}
size_t size = fb->len;
Serial.print(“Sending photo of size “);
Serial.print(size);
Serial.println(” bytes”);

client.write(reinterpret_cast<const uint8_t*>(&size), sizeof(size));
client.write(fb->buf, size);
// release the buffer
esp_camera_fb_return(fb);

Serial.println(“Closing connection…”);
client.stop();
}

Either I do not understand the Accelstepper operation or I do not understand the camera. All the copious print statements in the doMove function indicate that it is actually doing the move before it returns. So it seems that the statement

camera_fb_t* fb = esp_camera_fb_get();

is sending a photo it had previously taken.

Can anybody tell me what to change or direct me to the reference for the camera software.

Alan