SOLVED mapping a guage to a percentage for nextion

Using Arduino Programming Questions
1

hey all, im using a nextion display to show a guage for cpu usage
ive attached a picture of the guage im using for reference

my issue is in nextion a value of 0 sets the needle to 9 oclock on the guage

so i need to figure a way of mapping 0%-100% to a range of 270 degrees(the total desired arc) 315(0%) - 225(100%)
keeping in mind that as the percentage rises to 360 it will have to pass through 360 then 0 then 1 etc

im not smart enough to work this out haha ... my first thought was oh thats easy, ill just subtract the offset from the value untill i hit 360 degrees then add another offset, but that wont work as each scale has a different amount of points... then i though ill write down every value and do a buttload of if statements to replace each possible value one by one ... something tells me this is retarded.
i spose i really need to know how to bind say 0%-30% to like 270-360 and then like 30%-100% being 0-225
theres a better way? this might not even be a programming question but more one of maths?

gauge-for-temperature-md.png

2

What are the numbers to set the gauge to 0% CPU, 50% and 100%?

3

so 0% is 315degrees 50% is 90degrees and 100% is 225degrees

4

Spl1nt3rm4n:
so 0% is 315degrees 50% is 90degrees and 100% is 225degrees

assuming a linear relationship, then its would be a simple matter of doing a y=mx+c but to determine the value of c, we would need to know where does the needle like when it 0 degrees.

if the needle is horizontal pointing towards the left,
then 100% is -45degrees

50% is still 90degrees

0% is 225degrees

5 
if (cpu > 16)
  angle = map(cpu,16,100,0,255);
else if(cpu==0)
  angle = 90
else
  angle = 315-(cpu*16/45);
6

7

Thank you for the screenshot in reply #5

Similar to @ wildbill proposal but different equation! :wink:

if (cpu <50)//0<=cpu < 50%
  angle = 315-(4.5*cpu); 
else  //50<=cpu <=100%
  angle = (2.7*cpu)-45;

hope that helps...

8

edit ur a legend bill
got it going.. works great
couldnt have got there without help
ended up using

if (cload > 16)
 angle = map(cload,16,100,0,225);
else if(cload==0)
angle = 315;
else
angle = map(cload,1,15,316,360);

hmm.. looks like the right direction... i never saw the map function when researching this.
but i get unexpected results..
this is how i implemented your solutions..

/sherzaad
if (cload <50)//if less that 50%
  angle = 315-(4.5*cload);
else 
  angle = (2.7*cload)-45;

//wild bill
//if (cload > 16)
 // angle = map(cload,16,100,0,255);
//else if(cload==0)
//  angle = 90;
//else
//  angle = 315-(cload*16/45);

  myNex.writeNum("ctem.val", ctem);
   myNex.writeNum("ctem2.val", ctem);
      myNex.writeNum("cload2.val", cload);
   myNex.writeNum("cload.val", angle);
   myNex.writeNum("gtem.val", gtem);
   myNex.writeNum("gtem2.val", gtem);
      myNex.writeNum("gload2.val", gload);
   myNex.writeNum("gload.val", gload);
   myNex.writeNum("gclock.val", gclock);
 //  myNex.writeNum("gmem.val", gmem);
 //  myNex.writeNum("sclock.val", sclock);
   myNex.writeNum("cclock.val", cclock);

output the following

note cload2.val is the numerical cpu usage percent
and cload.val is the numerical degrees value going to the gauge

wild bill


ctem.val=41⸮⸮⸮ctem2.val=41⸮⸮⸮cload2.val=8⸮⸮⸮cload.val=313⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=40⸮⸮⸮ctem2.val=40⸮⸮⸮cload2.val=3⸮⸮⸮cload.val=314⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=40⸮⸮⸮ctem2.val=40⸮⸮⸮cload2.val=5⸮⸮⸮cload.val=314⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=7⸮⸮⸮gload.val=7⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=40⸮⸮⸮ctem2.val=40⸮⸮⸮cload2.val=7⸮⸮⸮cload.val=313⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=53⸮⸮⸮ctem2.val=53⸮⸮⸮cload2.val=11⸮⸮⸮cload.val=312⸮⸮⸮gtem.val=31⸮⸮⸮gtem2.val=31⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=1500⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=60⸮⸮⸮ctem2.val=60⸮⸮⸮cload2.val=28⸮⸮⸮cload.val=36⸮⸮⸮gtem.val=30⸮⸮⸮gtem2.val=30⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=67⸮⸮⸮ctem2.val=67⸮⸮⸮cload2.val=82⸮⸮⸮cload.val=200⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=68⸮⸮⸮ctem2.val=68⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=255⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=67⸮⸮⸮ctem2.val=67⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=255⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=68⸮⸮⸮ctem2.val=68⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=255⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=50⸮⸮⸮ctem2.val=50⸮⸮⸮cload2.val=93⸮⸮⸮cload.val=233⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=44⸮⸮⸮ctem2.val=44⸮⸮⸮cload2.val=5⸮⸮⸮cload.val=314⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=43⸮⸮⸮ctem2.val=43⸮⸮⸮cload2.val=9⸮⸮⸮cload.val=312⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=3⸮⸮⸮gload.val=3⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮







sherzaad



ctem.val=43⸮⸮⸮ctem2.val=43⸮⸮⸮cload2.val=9⸮⸮⸮cload.val=274⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=2⸮⸮⸮gload.val=2⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=42⸮⸮⸮ctem2.val=42⸮⸮⸮cload2.val=3⸮⸮⸮cload.val=301⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=41⸮⸮⸮ctem2.val=41⸮⸮⸮cload2.val=3⸮⸮⸮cload.val=301⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=42⸮⸮⸮ctem2.val=42⸮⸮⸮cload2.val=5⸮⸮⸮cload.val=292⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=6⸮⸮⸮gload.val=6⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=43⸮⸮⸮ctem2.val=43⸮⸮⸮cload2.val=4⸮⸮⸮cload.val=297⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=4⸮⸮⸮gload.val=4⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=45⸮⸮⸮ctem2.val=45⸮⸮⸮cload2.val=9⸮⸮⸮cload.val=274⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=4⸮⸮⸮gload.val=4⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=55⸮⸮⸮ctem2.val=55⸮⸮⸮cload2.val=8⸮⸮⸮cload.val=279⸮⸮⸮gtem.val=31⸮⸮⸮gtem2.val=31⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=1500⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=57⸮⸮⸮ctem2.val=57⸮⸮⸮cload2.val=33⸮⸮⸮cload.val=166⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=68⸮⸮⸮ctem2.val=68⸮⸮⸮cload2.val=82⸮⸮⸮cload.val=176⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=66⸮⸮⸮ctem2.val=66⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=225⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=68⸮⸮⸮ctem2.val=68⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=225⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=67⸮⸮⸮ctem2.val=67⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=225⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=68⸮⸮⸮ctem2.val=68⸮⸮⸮cload2.val=100⸮⸮⸮cload.val=225⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=1⸮⸮⸮gload.val=1⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮ctem.val=44⸮⸮⸮ctem2.val=44⸮⸮⸮cload2.val=63⸮⸮⸮cload.val=125⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=5⸮⸮⸮gload.val=5⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮
ctem.val=42⸮⸮⸮ctem2.val=42⸮⸮⸮cload2.val=3⸮⸮⸮cload.val=301⸮⸮⸮gtem.val=29⸮⸮⸮gtem2.val=29⸮⸮⸮gload2.val=0⸮⸮⸮gload.val=0⸮⸮⸮gclock.val=300⸮⸮⸮cclock.val=4900⸮⸮⸮

so when cload2 is 100 cload should be 225
and for cload2 is 50 should be 90
i think bill is closer.. dividing at 16 and doing map on either one

9

thanks for all the help guys, here is the final result....
just waiting on response from nextion about the second needle being buggy but im 99% there now

905×603 143 KB

10