Serial comunication with Arduino

OpenMV Products
1

Hello!

I need to create a comunication between OpenMV serial and Arduino serial: I want to read data from the first one and print them on the second one.

I did this program on OpenMV (cables connected at P4/P5 of camera):

from pyb import UART
uart = UART(3,9600, timeout_char = 1000)

thresholds_index = 0 #for yellow

Color Tracking Thresholds (L Min, L Max, A Min, A Max, B Min, B Max)

The below thresholds track in general yellow things.

thresholds = [(50, 100,-20,20, 30, 100)] # generic_yellow_thresholds

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.HQVGA) #240x160
sensor.skip_frames(30)
sensor.set_auto_gain(False) # must be turned off for color tracking
sensor.set_auto_whitebal(False) # must be turned off for color tracking
clock = time.clock()

while(True):
clock.tick()

Do your regular OpenMV image processing / etc

Only blobs that with more pixels than “pixel_threshold” and more area than “area_threshold” are

returned by “find_blobs” below. Change “pixels_threshold” and “area_threshold” if you change the

camera resolution. “merge=True” must be set to merge overlapping color blobs for color codes.

clock.avg()
img = sensor.snapshot().lens_corr(strength=1.8, zoom=1.0)

for blob in img.find_blobs([thresholds[thresholds_index]], pixels_threshold=50, area_threshold=50, merge=True):

These values are stable all the time.

img.draw_rectangle(blob.rect())
img.draw_cross(blob.cx(), blob.cy())
x= blob.cx()/13.12.54
y= blob.cy()/13.12.54

uart.write(“%d\n”%x)
uart.write(“%d\n”%y)

print(“x: %d\n”%x, end=‘’)
print(“y: %d\n”%y)
#print(clock.avg())

Arduino( MEGA) Code:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {
Serial.begin(9600);
mySerial.begin(9600);
}

void loop(){
if (mySerial.available()){
delay(100); // Wait for all data.
while (mySerial.available()) {
char d = mySerial.read();
str.concat(d);
}
}
char t[str.length()+1];
str.toCharArray(t, (sizeof(t)));
int intdata = atoi(t);

Serial.print(intdata);
Serial.print(“\n”);
delay(100);
}

But I don’t have any results.
Thanks for the help!

2

Can you wrap your code in the code tags the forum has so it’s more readable and fix the indentation?

3

OpenMV code:

# Yellow Color Code Tracking

import sensor, image, time, math
from pyb import UART
uart = UART(3,9600, timeout_char = 1000)

thresholds_index = 0 #for yellow
# Color Tracking Thresholds (L Min, L Max, A Min, A Max, B Min, B Max)
# The below thresholds track in general yellow things.
thresholds = [(50, 100,-20,20, 30, 100)] # generic_yellow_thresholds

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.HQVGA) #240x160
sensor.skip_frames(30)
sensor.set_auto_gain(False) # must be turned off for color tracking
sensor.set_auto_whitebal(False) # must be turned off for color tracking
clock = time.clock()

while(True):
    clock.tick()

    # Do your regular OpenMV image processing / etc
    # Only blobs that with more pixels than "pixel_threshold" and more area than "area_threshold" are
    # returned by "find_blobs" below. Change "pixels_threshold" and "area_threshold" if you change the
    # camera resolution. "merge=True" must be set to merge overlapping color blobs for color codes.

    clock.avg()
    img = sensor.snapshot().lens_corr(strength=1.8, zoom=1.0)

    for blob in img.find_blobs([thresholds[thresholds_index]], pixels_threshold=50, area_threshold=50, merge=True):

            # These values are stable all the time.
            img.draw_rectangle(blob.rect())
            img.draw_cross(blob.cx(), blob.cy())
            x= blob.cx()/13.1*2.54
            y= blob.cy()/13.1*2.54

            uart.write("%d\n"%x)
            uart.write("%d\n"%y)

            print("%d\n"%x,end="")
            print("%d\n"%y)
            #print(clock.avg())

Arduino code:

String str
#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {
Serial.begin(9600);
mySerial.begin(9600); 
}

void loop(){
if (mySerial.available()){
delay(100); // Wait for all data.
while (mySerial.available()) {
char d = mySerial.read();
str.concat(d);
}
}
char t[str.length()+1];
str.toCharArray(t, (sizeof(t)));
int intdata = atoi(t);

Serial.print(intdata);
Serial.print("\n");
delay(100);
}
4

Okay, your program on the OpenMV Cam is fine. The one on the Arduino isn’t written in a way that it will receive text easily.

Arduino supports a method called parse_int which can read an int on the serial port and will handle receiving data for you. Can you use that method to read the two unit values you send and then print what parse_int returns?