Store › Forums › Digit Shield › Bugs/Problems › Suggestion about fixed point use
- This topic has 2 replies, 2 voices, and was last updated 12 years, 6 months ago by
Baby Bertha.
-
AuthorPosts
-
February 28, 2012 at 9:17 am #512
Baby Bertha
MemberHi – I just received a digit shield, had it assembled and working without a hitch in 30 minutes or so. Nice 🙂
I’m just experimenting and familiarising myself with the API, but one thing I noticed straight away, since it affects my project. I used setDecimalPoint( 2, true ) to set a fixed point position after the second digit. Otherwise the configuration is the default, with leading zero blanking on. I expected that the LZB would take this into account, so that it would only blank leading zeroes once the “fixed point” format had been taken into account, so for example, 0 would be displayed as 0.00, 1 as 0.01, etc. Of course it doesn’t – the point itself is blanked until there are at least 3 digits. I can’t think of any good use for that behaviour (you might be able to suggest one!) and I’m sure I can figure out a workaround, but can I suggest that the leading zero blanking is made smarter to give the expected outcome for a fixed point display? Or perhaps have a “fixed point mode” that can smarten up the LZB behaviour.
Thoughts?
February 29, 2012 at 1:53 pm #1068Michael
KeymasterI think you are misinterpretting the meaning of the API functions [tt:2bo3kbzi]setDecimalPoint[/tt:2bo3kbzi] and [tt:2bo3kbzi]setDigit[/tt:2bo3kbzi] They are simply a way to directly control the LEDs directly without any interpretation by the library about how to display values. They are an alternative to using [tt:2bo3kbzi]setValue[/tt:2bo3kbzi]. So, [tt:2bo3kbzi]setDecimalPoint(2, true)[/tt:2bo3kbzi] does not mean “always display the decimal in position 2 when I display numbers”. It just means “turn on the decimal for digit 2”. It is not a “fixed point mode” for displaying values. Hope that makes sense.
You could implement a “fixed point mode” easily enough, I think.
int fixedPointModePosition = -1;
void setFixedPointMode(int position) {
DigitShield.setPrecision(position);
fixedPointModePosition = position;
}
void setFixedPointValue(int v) {
if (fixedPointModePosition < 0) {
// not in fixed point mode
DigitShield.setValue(v);
return;
} else {
DigitShield.setValue(v / fixedPointModePosition);
}
}
Or something like that. I wrote that really fast.
March 2, 2012 at 5:50 am #1071Baby Bertha
MemberI understand that, but nevertheless, the setDecimalPoint API interacts with the leading zero blanking in a way that doesn’t make any sense (and probably wasn’t anticipated). LZB should blank zeroes, but never points! As it stands it basically means I have to implement the digit drive code myself, since the API doesn’t work in a way that’s useful here (I’m not saying the standard setValue methods aren’t useful, they are). In fact using a floating point value works pretty much how I need it to, so as long as that proves to be fast enough it will do the job nicely.
-
AuthorPosts
- You must be logged in to reply to this topic.