<script language="JavaScript">
var form;
var win_ubrr, fosc, baud; var row, ubrr, err;
function init() { form = document.forms["data"];
form.fosc.value="1.000000"; }
function round (x, n) { n = Math.pow (10, n); x = Math.round (n*x)/n; return x; }
function get_ubrr (baud, m) { var f = 1000000*fosc; var ubrra, bauda, erra; var ubrrb, baudb, errb;
ubrr = f/(m*baud)-1; ubrra = Math.floor (ubrr); ubrrb = Math.ceil (ubrr); bauda = f/(m*(ubrra+1)); baudb = f/(m*(ubrrb+1)); erra = bauda/baud-1; errb = baudb/baud-1;
if (Math.abs (erra) < Math.abs (errb)) { err = erra; ubrr = ubrra; } else { err = errb; ubrr = ubrrb; }
err = round (err*100, 1); if (ubrr >= 10) ubrr += "=0x" + ubrr.toString(16);
if (Math.abs (err) < 0.21) { err = ""+err+""; ubrr = ""+ubrr+""; } else if (Math.abs (err) > 10) { err = "–"; ubrr = err; } }
function get_row (baud) { var color = ((row & 1) == 0) ? "#ffffff" : "#f0f0ff"; var html = "<tr bgcolor=\""+color+"\">"; var baudstr = baud; var ubrr0, err0; var ubrr1, err1;
row++;
if (baud > 9600) { baudstr = "" + (baud / 1000) + "k"; }
if (baud > 250000) { baudstr = "" + (baud / 1000000) + "M"; }
get_ubrr (baud, 16); ubrr0 = ubrr; err0 = err;
get_ubrr (baud, 8); ubrr1 = ubrr; err1 = err;
html += "<td>"+baudstr+"</td>"; html += "<td align=\"center\">"+ubrr0+"</td>"; html += "<td align=\"center\">"+err0+"</td>"; html += "<td align=\"center\">"+ubrr1+"</td>"; html += "<td align=\"center\">"+err1+"</td>"; html += "</tr>\n";
return html; }
function write_ubrr_table () {
var html = "row = 0;
html += "| Baud Rate (bps) | ";
html += "fosc = "+fosc+" MHz | |||
| U2X = 0 | U2X = 1 | |||
| UBRR | Error (%) | "; html += "UBRR | Error (%) | |
// alert (html);
win_ubrr.document.writeln (html); }
function open_ubrr_window (val) { fosc = parseFloat (val);
if (win_ubrr) win_ubrr.close(); win_ubrr = window.open ("about:blank", "ubrr", "toolbar=no, menubar=no, width=400"); win_ubrr.focus(); win_ubrr.document.close(); // win_ubrr.document.open(); // win_ubrr.document.location.href = "about:blank";
var html = "<html>\n"; html += "<head>\n" html += "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=iso-8859-1\">\n"; html += "<meta name=\"Author\" content=\"Georg-Johann Lay\">\n"; html += "<title>ATMega8 Baudrate, fosc = "+fosc+" MHz</title>\n"; html += "</head>\n" win_ubrr.document.writeln (html);
html = "<body bgcolor=\"white\" text=\"black\">\n"; win_ubrr.document.writeln (html); write_ubrr_table (fosc, baud); html = "</body>\n"; html += "</html>\n"; win_ubrr.document.writeln (html); win_ubrr.document.close(); }
function write_freq_button (frq) { html = "<input type=submit onclick=\"open_ubrr_window("+frq+")\" SIZE=\"120\" VALUE=\" "+frq+" MHz \">";
document.writeln (html); }
</script>