# Measure the distance
#
# This example shows off how to measure the distance through the size in imgage
# This example in particular looks for blue pingpong ball.

import sensor, image, time
from pyb import UART
import ujson

# For color tracking to work really well you should ideally be in a very, very,
# very, controlled enviroment where the lighting is constant...
blue_threshold   = ((69, 88, -35, -15, -53, 0))
# You may need to tweak the above settings for tracking green things...
# Select an area in the Framebuffer to copy the color settings.

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.RGB565) # use RGB565.
sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.
sensor.skip_frames(10) # Let new settings take affect.
sensor.set_auto_whitebal(False) # turn this off.

clock = time.clock() # Tracks FPS.


uart = UART(1,9600)
K=500#the value should be measured

def find_max(blobs):
    max_pixels=0
    for blob in blobs:
        if blob[4] > max_pixels:
            max_blob = blob
            max_pixels = blob[4]
    return max_blob

while(True):
    clock.tick()
    img = sensor.snapshot()

    blobs =img.find_blobs([blue_threshold])
    if blobs:
        max_blob = find_max(blobs)
        img.draw_rectangle(max_blob.rect())
        img.draw_cross(max_blob.cx(),max_blob.cy())
        pcx = max_blob.cx()
        pcy = max_blob.cy()
        cxy = {"cx":pcx,"cy":pcy}
        uart.write(ujson.dumps(cxy)+'\r\n')
        print(cxy)

#include <ArduinoJson.h>

volatile int cx;
volatile int cy;
volatile char c;
String json;

void setup(){
cx = 0;
cy = 0;
c = 0;
json = "";
Serial.begin(9600);
}

void loop(){
if (Serial.available() > 0) {
c = char(Serial.read());
json = String(json) + String(c);
if (c == '}') {
StaticJsonBuffer<200> jsonBuffer;
JsonObject& root = jsonBuffer.parseObject(json);
if (!root.success()) {
Serial.println("JSON failed!");
}
int cx = root["cx"];
int cy = root["cy"];
Serial.print("cx = ");
Serial.print(cx);
Serial.print('\t');
Serial.print("cy = ");
Serial.println(cy);
json = "";
}
}
}