RC Time problem
kenmac
Posts: 96
I have been working on the CTR/RC Time program, displaying the PHSA number on LCD.
It works OK, reading/displaying the number on the first pass through the loop.
However, subsequent passes (thru loop) only read the number as 0.
I added in a LED to trap if the PHSA = or > 0 on each pass - it confirms what was displayed.
I used a fixed 10K/0.1uF combination on Pin 8.
The code used is as follows: (display stuff left out)
Can anyone spot any obvious code error or know why the PHSA number is 0 for all passes except the first?
kenmac
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Perth, Western Australia
Time Zone = GMT + 8
It works OK, reading/displaying the number on the first pass through the loop.
However, subsequent passes (thru loop) only read the number as 0.
I added in a LED to trap if the PHSA = or > 0 on each pass - it confirms what was displayed.
I used a fixed 10K/0.1uF combination on Pin 8.
The code used is as follows: (display stuff left out)
con
_clkmode = xtal1 + pll16x ' System clock → 80 MHz
_clkfreq = 5_000_000
var
long num
pub start
dira[noparse][[/noparse]16..17]~~ ' set as output
ctra[noparse][[/noparse]30..26] := %01000 ' set counter mode = pos detect
ctra[noparse][[/noparse]5..0] := 8 ' set CTR to use Pin 8
frqa := 1 ' number to increment PHSA
repeat
{ charge capacitor & time discharge (accumulate number in PHSA) }
outa[noparse][[/noparse]8]~~ ' set Pin8 high to charge capacitor
uSdelay(5000) ' wait 5mS
phsa~ ' clear PHSA
dira[noparse][[/noparse]8]~ ' change Pin 8 to input - commence discharge
uSdelay(50_000) ' wait to allow for discharge time
num := phsa ' read PHSA
!outa[noparse][[/noparse]16] ' visual indicate that number is read
if num == 0
outa[noparse][[/noparse]17]~~ ' num > 0
else
outa[noparse][[/noparse]17]~ ' num = 0
uSdelay(20_000_000) ' delay between readings
pub uSdelay(DelayuS) ' Delay microseconds
waitcnt((clkfreq/1_000_000) * DelayuS + cnt)
Can anyone spot any obvious code error or know why the PHSA number is 0 for all passes except the first?
kenmac
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Perth, Western Australia
Time Zone = GMT + 8
Comments
The actual code area reads like this:
kenmac
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Perth, Western Australia
Time Zone = GMT + 8
In the loop I used Dira[noparse][[/noparse]8]~ where it should have been Outa[noparse][[/noparse]8]~ .
Just shows you sometimes need someone else to look at it.
Thanks, deSilva.
I know you are very busy - How do you get the time to handle simple stuff like this?
Anyway, I'm grateful for the assistance.
Now for some sleep!
kenmac
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Perth, Western Australia
Time Zone = GMT + 8
Soon I shall spend hours finding such problems in other person's code - I am practicing
My last post was incorrect - a decision by a "tired mind".
Anyway, with a fresh mind it is now obvious.
The reason why it didn't work correctly was that the Pin mode needed to be toggled at each pass thru the loop, and so the Dira[noparse][[/noparse]8]~~ needed to be in the loop for this to happen.
It has been corrected and the program now works OK.
kenmac
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Perth, Western Australia
Time Zone = GMT + 8