I'm still pretty knew to Arduino and am trying to understand the serial.read command. I have read through a lot of the information online, but still do not understand why my code doesn't work correctly. Specifically, it correctly displays in the serial monitor the ASCII value of the key that was entered. However, the if statement doesn't correctly function and any key triggers the tone. Im a at a loss on how to fix this. All advice is appreciated! Thanks!
int input=0; //input character
void setup() // Built in initialization block
{
Serial.begin(9600); // Set data rate to 9600 bps
while(input!=114) //if the r key hasnt been pressed, keep going
{
while(Serial.available()==0){}
input = Serial.read();
Serial.println(input);
if (input=117) //if the user put u, stop the servo from moving
{
tone(9, 2000, 700);
}
}
}
void loop()
{}
Just a bit of nitpicking, but would your code not be more readable when you actually put the letters in instead of numbers?
e.g
while(input!='r')
If you crank up the warning levels in the IDE (file -> preferences -> compiler warnings -> all), you will get a warning in the output window that indicates that there might be something wrong with your if statement (see Blackfin's comment above).
C:\Users\sterretje\AppData\Local\Temp\arduino_modified_sketch_991178\sketch_sep28a.ino: In function 'void setup()':
C:\Users\sterretje\AppData\Local\Temp\arduino_modified_sketch_991178\sketch_sep28a.ino:14:20: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
if (input = 117) //if the user put u, stop the servo from moving
If you enter r from the InputBox of the Serial Monitor (Fig-1), what action (you say) your Arduino UNO should take.
If you enter u from the InputBox of the Serial Monitor (Fig-1), what action (you say) your Arduino UNO should take.
Figure-1: Serial Monitor of Arduino IDE
Remember that when you enter a character (Say: r) in the InputBox of the Serial Monitor and then click on the Send button, it is received by UNO and is saved in a FIFO type Buffer. So at the UNO side, your first job would be to check if any character has arrived in the FIFO Buffer and then read/store it in a char type variable. To do this task, I usually execute the following codes:
void loop()
{
byte n =Serial.available();
if (n != 0) //there is at least one character in the FIFO Buffer
{
char x = Serial.read(); //x contains r (ASCII code of r = 0x72 = 114) if r was entered
if( x == 'r') //r has come from the InputBox
{
//do this
Serial.print(x); //received character goes back to OutputBox of Serial Monitor
}
if(x == 'u') //u has arrived from the InputBox
{
//do this
}
}
}
GoForSmoke:
I don't want to spend 30 minutes reading code to find out, does the library contain blocking code?
Absolutely not
I wrote it for communication between a custom Arduino hand controller and Arduino RC airplane, so speed, reliability, and "non-blockingness" was integral to the library design
Here is how I handle incoming data as proof:
/*
int8_t SerialTransfer::available()
Description:
------------
* Parses incoming serial data, analyzes packet contents,
and reports errors/successful packet reception
Inputs:
-------
* void
Return:
-------
* int8_t - Error code
*/
int8_t SerialTransfer::available()
{
if (port->available())
{
while (port->available())
{
uint8_t recChar = port->read();
switch (state)
{
case find_start_byte://///////////////////////////////////////
{
if (recChar == START_BYTE)
state = find_overhead_byte;
break;
}
case find_overhead_byte://////////////////////////////////////
{
recOverheadByte = recChar;
state = find_payload_len;
break;
}
case find_payload_len:////////////////////////////////////////
{
if (recChar <= MAX_PACKET_SIZE)
{
bytesToRec = recChar;
state = find_payload;
}
else
{
state = find_start_byte;
return PAYLOAD_ERROR;
}
break;
}
case find_payload:////////////////////////////////////////////
{
if (payIndex < bytesToRec)
{
rxBuff[payIndex] = recChar;
payIndex++;
if (payIndex == bytesToRec)
{
payIndex = 0;
state = find_checksum;
}
}
break;
}
case find_checksum:///////////////////////////////////////////
{
uint8_t calcChecksum = findChecksum(rxBuff, bytesToRec);
if (calcChecksum == recChar)
state = find_end_byte;
else
{
state = find_start_byte;
return CHECKSUM_ERROR;
}
break;
}
case find_end_byte:///////////////////////////////////////////
{
state = find_start_byte;
if (recChar == STOP_BYTE)
{
unpackPacket(rxBuff, bytesToRec);
return NEW_DATA;
}
return STOP_BYTE_ERROR;
break;
}
default:
{
Serial.print("ERROR: Undefined state: ");
Serial.println(state);
state = find_start_byte;
break;
}
}
}
}
else
return NO_DATA;
return CONTINUE;
}
Very good and I see that it will work with blocking code due to that while available loop even though -it- does not block. My stuff is not so robust, it expects sketches to stay ahead of every available char.
