Web BASIC
 

BASICweb allows for basic code to be embedded in the web pages much like PHP or JavaScript
Global variables may be accessed from the User BASIC program.  The intention is not to place your BASIC code in this program, but to interact with your program from a web page.  For example if you put an endless loop in the <?BASIC embedded in the web page, the web page will hang.  <>BASIC can not call BASIC functions or subroutines in the user code.

Example: Add reading and setting a User variable through the web page.

Here is a modified version of the web page loaded from Web Services and a second webpage that resets the value of X

source for simple.htm

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html; charset=ISO-8859-1" http-equiv="content-type">
  <title>simple page</title>
</head>
<body>
<?BASIC
  print "the VALUE of x is ";x 
?>
<br>
<br>
<a href="zero.htm">Zero X</a>
</body>
</html>

Now from Code page of ARMweb enter the following program (its can be accessed at armweb.htm)

 


WHILE 1
  IO(55) = X AND 1   ' Flash the LED
  X = X + 1
  WAIT (500)
LOOP
RUN

The program is running and the value of X is incremented every half second.
Browse to http://ARMweb/simple.htm

Refreshing the browser will show the updated values of X.

Example: Executing a BASIC command from a web page.

To the above example we will add a method to set the variable x to 0, by accessing another web page that runs a BASIC program.  This may also be accomplished with CGI, see the CGI examples .

First add an anchor to another web page that will be served by the ARMweb

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html; charset=ISO-8859-1" http-equiv="content-type">
  <title>simple page</title>
</head>
<body>
<?BASIC
  print "the VALUE of x is ";x
?>
<br>
<br>
<img style="width: 500px; height: 80px;" alt="planes" src="banner1.gif">
<a href="zero.htm">Zero Y</a>
</body>
</html>


Next create another page zero.htm that executes a very short BASIC program to zero the variable y.  This page also returns to the original page.

source for zero.htm

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html; charset=ISO-8859-1" http-equiv="content-type">
  <title>simple zero page</title>
</head>
<body>
<?BASIC
  print "the VALUE of x was ";x;"<br>"
  x = 0
  print "the VALUE of x is now";x
?>
</body>
</html>
<  
/PRE>
  
<  /FONT>



Some notes, currently errors in the BASIC embedded in HTML are not flagged, 
so be careful, but they will be visible to the console of BASICtools over the 
USB connection.


The meta tag highlighted will return you to the original page after 1 second, 
though not all browsers support this.


For a CGI method to accomplish the same see the CGI 
examples .


WEB BASIC limits


The BASIC code between <?BASIC and ?> is limited to 1450 
characters.


The output from a web BASIC program must not exceed 1460 characters.


If the web BASIC contains an infinite loop, the server will hang waiting for 
the loop to complete.


The Pre-processor is not available to WEB BASIC inside the HTML.  That 
includes #include, #ifdef,  #define...


              
             
      The code between <?BASIC ... ?> and 
the output is also sent to the UART0 (and via USB Dongle 
or mbed USB serial port to BASICtools). 


See also