Sending X Y Coordinates Through Serial USB?

i brannew processing/arduino.
taking class @ school, class behind me, , teacher won't me out until class catches up.

i need figure out how x , y coords arduino through serial usb.


i cant figure out atoi thing. (but understand should - ascii integer)

so.... arduino takes bites, or something.
you have convert ascii stuff.
and have number 255.


i thought simple task. need coords program , taking lot longer want to.


spent few hours looking @ other posts!

i pretty sure

http://www.arduino.cc/cgi-bin/yabb2/yabb.pl?num=1231650517

is trying do.

i cant make sense of it.

are x, y coords being sent processing? strings or numbers? sent 1 @ time, or together?

if data being sent processing string data, , numbers sent together, need include sort of beginning of packet , end of packet markers, delimiter between values. send string this:

<12, 45>

the arduino can read serial data, discarding data until sees <. then, knows data stream contains valid data.

it reads 1 character @ time, looking character represents digit, comma, space, > or <.

if character represents digit, converts character number, subtracting '0' ('8' - '0' = 8; '5' - '0' = 5). multiplies previous value 10 , adds new value:

code: [select]

x *= 10;
x += n;

if x 8 , n 4, 8 * 10 = 80, plus 4 = 84.

if character is, instead, comma or space, discarded, rest of string goes in y. if character >, end of packet has been received, , x , y can used.

if character <, packet not sent, values in x , y reset, , new packet processed.

if data sent numbers, 2 bytes (which limited 0 255) can read , used.

Arduino Forum > Forum 2005-2010 (read only) > Software > Interfacing > Sending X Y Coordinates Through Serial USB?

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