I have written a simple code that sends some information to the arduino and I have added some handshaking. The problem is that it works 80% of the time. The arduino send the character "/" and the (lets say another arduino for simplicity) send throttle roll pitch yaw.
Like so:
Arduino 1
if (input == '/')
ons.write(THROTTLE);
ons.write(ROLL);
ons.write(PITCH);
ons.write(YAW);
ons.write(AUX1);
I know this code isnt gonna compile but you get the idea. The problem is that sometimes the channels get mixed up (like throttle reads roll). Oh and I should add there is a delay of 100 milliseconds between sending data.
So my question is what would be a better handshaking method?
So my question is what would be a better handshaking method?
The problem isn't with handshaking. The problem is with your assumption that serial data delivery is guaranteed. It is not.
There may be further problems if the values you are sending are not byte sized. The snippets you posted leave a lot to be desired.
By the way, there is a convention that all capital letter names are constants. In your snippets, it hardly makes sense for THROTTLE, etc. to be constants.
I have had some success with the "Serial.find()" function, it works a treat for me when trying to pick up a character or a string and then act upon that when you get it!
The problem isn't with handshaking. The problem is with your assumption that serial data delivery is guaranteed. It is not.
Ah huh! So thats the problem
By the way, there is a convention that all capital letter names are constants. In your snippets, it hardly makes sense for THROTTLE, etc. to be constants.
I didnt know that. I just wrote it with capitals to make it clearer to me.
Ok I ran onto another problem. If I lose the connection, the arduino doesnt know it and it continues to send the previous values stored. Now I want to keep these vlues and not set them all to zero at each loop. I thought that simply writing this would work:
if((!Serial.available() > 0) && delaytime > 500){
do something
However, that never happens. Before you ask, yes I have verified that delaytime is incremented. What would be the approach to knowing when the connection is lost and doing this without adding extra code on the sending arduino side?
What I mean is the if is never true. I have set it to a led and it never turns on. Curious thing is that if i put only the serial.available an not the delay, the led turns on. Also if I set the delay in the same sceth to blink the led, it does it properly. So my question is why don't they work together(like in the code suggested before)?
Theelectronicguy:
I thought that simply writing this would work:
if((!Serial.available() > 0) && delaytime > 500){
do something
I find that code mildly disconcerting. Could you post your actual code, not some sort of "this is sort-of what it does" code? Like, "do something" is not valid C.
Ok well basically I would appreciate an example of what kind of code should be written because I have no idea :P. Lets say I want the arduino to turn the led ON when the serial connection has failed for more than 1 second(aand off when the connection has been established). This is my current code:
#include <Servo.h>
Servo Throttle; // create servo object to control a servo
Servo Roll;
Servo Pitch;
Servo Yaw;
Servo Aux1;
int throttle;
int roll;
int pitch;
int yaw;
int aux1;
long previousMillis = 0;
void setup()
{
Throttle.attach(2); // attaches the servo on pin 9 to the servo object
Roll.attach(3);
Pitch.attach(4);
Yaw.attach(5);
Aux1.attach(6);
Serial.begin(115200);
throttle = 0;
roll = 90;
pitch =90;
yaw = 90;
aux1 = 0;
}
void loop()
{
switch(GetFromSerial()){
case 'T':
throttle = (GetFromSerial() + 45);
break;
case 'R':
roll = (GetFromSerial() + 45);
break;
case 'P':
pitch = (GetFromSerial() + 45);
break;
case 'Y':
yaw = (GetFromSerial() + 45);
break;
case 'A':
aux1 = (GetFromSerial() + 45);
break;
}
long currentMillis = millis();
if(currentMillis - previousMillis > 50) {
Throttle.write(throttle);
Roll.write(roll);
Pitch.write(pitch);
Yaw.write(yaw);
Aux1.write(aux1);
previousMillis = currentMillis;
}
}
int GetFromSerial() {
while (Serial.available()<=0) {
}
return Serial.read();
}
Yes thank you I just couldnt get my head around how (and where) to put the lastreceiveserial. Thank you for the example, Ill try it now.
45? What does adding a '-' or 45 to the serial byte accomplish?
Well, to control the quadcopter, I had to send servo values between 45 and 141 so 141 was over the 128 byte value limit(and I can't send unsigned bytes from android processing i think). This also prevents negative values. I guess I could of put it like this instead:
