20mV is high???

grkblood13

hey, can any1 tell me why this program for a set of tripwires wont read IN9 as 0 when it trips low to 20mV?

Aircraft_Ident VAR Word
Aircraft_pass VAR Word
Current_weight VAR Word
Aircraft_weight  VAR Word
Yes_No VAR Bit
 

begin:
IF IN9 = 0 AND IN10 = 1 THEN calc    'tells program to weigh'
IF IN9 = 1 AND IN10 = 0 THEN standby   'someone is walking through scale backwards'
IF IN9 = 1  AND IN10 = 1  THEN begin   'loops tripwire'
 
standby:
DO
IF IN9 = 1 OR IN10 = 1 THEN  begin   'this is just to make sure there are no glitches'
LOOP
 
calc:
location CON 0
i VAR Nib
total VAR Word
Aircraft_Ident = 0
Aircraft_Ident = 50              'test value
DEBUG DEC Aircraft_Ident
PAUSE 1000                       'delay to compensate for time to get on scale'
total = 0
FOR i = 1 TO 15
total = total + (INS & $01FF) - Aircraft_Ident     'takes reading from IN0 - IN8'
PAUSE 100                         'this delay is because the converter is running at 10 Hz'
NEXT
total = total / 15
WRITE location,total
DEBUG CR, DEC total

Phil Pilgrim (PhiPi)

Any action that depends on IN9 being zero also depends on IN10 being one. Are you sure BOTH conditions are being met?

-Phil

grkblood13

they're both being met. the only thing that i can get to work is the both high case. ive got a multimeter hooked up and is reading about 15mV when low b/c i changed a resistor. but the prog still wont read low. the pins are arbitrarely reading high also, im guessing they're supposed to though

Martin Hebel

Also, do you have pull-down resistor on those inputs so they are not floating high? Use a simple loop of ? IN9 and ? IN10 to watch their states. You don't say really how the electrical connections are.
-Martin

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StampPlot - GUI and Plotting, and XBee Wireless Adapters
Southern Illinois University Carbondale, Electronic Systems Technologies

Chris Savage

Exactly how is the pin connected? If it’s floating in the LOW state it may not actually be LOW.

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Chris Savage
Parallax Tech Support

grkblood13

i have the load wire from the tripwire coming into a node with a resistor running to ground and a wire from the node to the pin. when it trips the pin reads 15mv. when not tripped it read 7V

Phil Pilgrim (PhiPi)

Seven volts? Connected directly to the Stamp pin? You may have fried the input circuitry.

-Phil

grkblood13

i can also run the resistor to Vdd and switch the order around.
but i think it might be fried, i tried writing

LOW 9
LOW 10

P10 would read low but P9 would read like 5 volts on the multimeter