Sending multi digit serial numbers to the arduino.

[Mcfly]

Im working on my widget, and i need a way to send an 8 bit binary number to the arduino.  I know how to send a single digit number to the arduino, but I'm running into ascii problems and who knows what else.  Has anyone ever done this before, and can point me in the right direction?

[Rerouter]

when you mean binary, why would ascii be involved? you send it as a byte, arduino accept bytes, its the conversion to decimal or what ever standard you want to follow, if not decimal or hex might require a look up table,

[ejeffrey]

The easiest, most portable, and most generic way is to convert your number to a decimal ASCII string.  You use sprintf() or the equivalent on your host and use the int() conversion function on the arduino.  If you are using native C on your microcontroller you want the strtod() function.

The only real downside to that is that it isn't very efficient.  A 2 byte word can take up to 6 characters.  This is not a problem for most applications, but if you need high throughput or low latency and are stuck with the slow RS232 port you can do better with binary data.

[NiHaoMike]

Just send it on the line. 8 bits (one byte) is the standard "unit" size on RS-232 so you don't need to do any framing. Things get much more complicated when sending sequences of multiple bytes. A good way of framing uses a signal that cannot possibly be a data value. In RS-232, it can be done by sending a "break".

[electrode]

Not enough info in question. Give us an example of what you're trying, what you want, and what you're getting.

Communication should be trivial. I use pySerial.

[bsiswoyo]

Im working on my widget, and i need a way to send an 8 bit binary number to the arduino.  I know how to send a single digit number to the arduino, but I'm running into ascii problems and who knows what else.  Has anyone ever done this before, and can point me in the right direction?

please visit my blog about this:

http://bsiswoyo.lecture.ub.ac.id/2012/08/arduino-tutorial-how-to-turn-onoff-8-led-using-visual-basic/

best regard
bambang siswoyo

[jucole]

please visit my blog about this:
http://bsiswoyo.lecture.ub.ac.id/2012/08/arduino-tutorial-how-to-turn-onoff-8-led-using-visual-basic/

hi, are you sure the source code is in the file "Source_LEDWidget_Arduino.rar" ?

[jucole]

I've never used Arduino only Microchip but a quick Google around and it looks really easy using the Serial.Read like ... "incomingByte = Serial.read();"
Just make sure that if you're using VB6 etc that you're actually sending the number as a byte and not a byte sequence of ascii values.

[bsiswoyo]

hi jucole.

Yes, there are a setup file and source code freely can be downloaded.

[jucole]

hi jucole.
Yes, there are a setup file and source code freely can be downloaded.

hi , I see the Arduino code and the vb6 setup exe etc,  but the vb6 code "Form1.frm" is not in the rar file "Source_LEDWidget_Arduino.rar" ?

[jeremy]

This is a pretty sneaky problem, I'm sure there is a libc way to do it but I usually just

Code: [Select]

uint32_t get_number(char size) {

uint32_t output_number = 0;

for (char i=0; i<size; i++) {
// get some characters, convert ascii into the actual number, add it in
// note that '0' is 48, the ascii code for the zero character
    output_number += Serial.read() - '0';

    output_number *= 10; // shift everything up by one digit
}
}

This assumes that you send digits in the most significant to least significant order ie if you want to send 1234 you would send '1', '2', '3', '4'. So to get an 8 digit number you would just go

Code: [Select]

uint32_t  num = get_number(8);
But using a 32 bit integer on an 8 bit micro is really inefficient, you should just store it in an array and process it from there.

Code: [Select]

#define NUM_SIZE 8

char buffer[NUM_SIZE];
for (i=0; i<NUM_SIZE; i++) buffer[i] = Serial.read() - '0';
Good luck!