Use SpryValidationTextField to check MAC address

Question

Goal: I would like to have a data entry check in a text field
that confirms a properly formed MAC address was entered.
My attempt: I created a SpryValidationTextField of type
custom with a pattern 00-00-00-00-00-00 and 'Enforce Pattern'
ticked. The issue is that the system will not allow me to enter
letters A-F for hexadecimal vlaues but only digits 0-9.
Vice versa if I enter the pattern AA-AA-AA-AA-AA-AA the
system will not allow me to enter any digits 0-9 but all
characters.
What I need is a check that allows all values 0-9/A-F with
letters preferably automatically converted to capital letters, when
entered in small characters, while preserving the integrity of the
pattern 00-00-00-00-00-00.
Can anyone help?

Answer 1

A slight modification to the suggestions and it now works
perfect. The improvement handles the error messaging perfectly well
but also ensures that a complete MAC address is entered ( the
preliminary solution given below allowed accepted a MAC address of
16 characters as valid).
Thanks for cw2ureg and V1 Fusion for their input. All credit
to them
HTML:
<span id="sprytextfield1">
<input type="text" name="mac" value="" size="17" />
<span class="textfieldRequiredMsg">A value is
required.</span><span
class="textfieldMinCharsMsg">Minimum number of characters not
met.</span><span class="textfieldMaxCharsMsg">Exceeded
maximum number of characters.</span><span
class="textfieldInvalidFormatMsg">Not a valid MAC
address</span></span>
Constructor:
var sprytextfield1 = new
Spry.Widget.ValidationTextField("sprytextfield1", "none",
{validation: fnValidateMacAddress, validateOn:["blur"],
hint:"00-00-00-00-00-00", minChars:17, maxChars:17});
Function:
function fnValidateMacAddress(macaddr) {
var reg1 =
/^[A-Fa-f0-9]{1,2}\-[A-Fa-f0-9]{1,2}\-[A-Fa-f0-9]{1,2}\-[A-Fa-f0-9]{1,2}\-[A-Fa-f0-9]{1,2 }\-[A-Fa-f0-9]{1,2}$/;
var reg2 =
/^[A-Fa-f0-9]{1,2}\:[A-Fa-f0-9]{1,2}\:[A-Fa-f0-9]{1,2}\:[A-Fa-f0-9]{1,2}\:[A-Fa-f0-9]{1,2 }\:[A-Fa-f0-9]{1,2}$/;
if (reg1.test(macaddr)) {
return true;
}else if (reg2.test(macaddr)) {
return true;
} else {
return false;