Programming (Ping.spin) Trouble w/ PING)))

mophead

Hello,

Im having trouble with the method (Ticks) in the object (Ping.spin) which is the example program for the Propeller Microcontroller in the ping sensor’s datasheet. Specifically I can’t get the method Ticks to return a correct time interval between the rising edge and the falling edge of the echo pulse, all I get now is some constant value because I tried a smaller resistor (220 Ohm). With the 1k resistor the program could sense the rising edge but not the falling edge, so it would always freeze the program

The following code of concern is below
waitpne(0, |< Pin, 0)
cnt1 := cnt
waitpeq(1, |< Pin, 0)
cnt2 := cnt
Microseconds := (||(cnt2 - cnt1) / (clkfreq / 1_000_000)) >> 1

More info: Gadget Gangster Propeller Platform
5V power supply to board and sensor
220 Ohm

The sensor is functioning properly, because I was able to get it to work with my arduino mega board which correctly calculated the time with the pulseIn() function. Any help or further explanation of what’s really going on with this code would be truly appreciated.


Thanks,
mophead

Mike Green

You copied the code wrong. The waitpeq statement's 1st argument is 0. Look again at the documentation.

The 220 Ohm resistor is way too low. You should actually use something like 2.2K. With a 220 Ohm resistor, the PING can damage the Propeller's I/O pin.

mophead

Thanks for your input, I copied the wrong code but later after i already posted the thread fixed it so that waitpeq(0, |<Pin,0) but had the same results then as before. I added > 1k ohms of resistance, but, unlike before, the ping sensor's LED doesn't blink which (correct me if I'm wrong) represents the actual ultrasound pulse. Also nothing outputs to the terminal. Man I'm stuck, I know the code isn't wrong, I've tried other pins, I've tried a smaller resistance which did blink the LED but as u said was dangerously low. Is there anything else I could try or test to provide you with more information?

Thanks again for your help,
mophead

dandreae

Are you able to try a resistor of 2.2K or 3.9K?

Dave

Ray0665

Waitpeq and Waitpne use 32 bit arguments for the first two arguments
waitpeq( |<Pin, |<Pin, 0) and waitpne( |<Pin, |<Pin, 0)
not waitxx(1,|<Pin,0) (unless your ping is attached to pin 0)

Pin could also be multiple pins ie $0000_0000_0000_00FF for the first 8pins