Help Needed about Ping Ultrasonic

LionRobot

Hello everyone,

I have already search thie forum and google it but I do not find the answer.

I am using Ping Ultrasonic sensor(three Pins)

I try to use 7 ultrasonics at the same time. Is it possible?

I am using PIC 16F877 microcontroller and 2840 development board from Basic Micro.

I can use one Ping Ultrasonic. It is work perfectly but how to use 7 Pings at the same time or one by one?

I mean that I use timer1 to count the time (how long the echo come back)and to caculate the distance by echo.

Since same pin is used to transmit and recieve a signal, I need to keep firing and receiving.

There are 7 Ping Ultrasonics but I do not have 7 timers so how should I do ?

Or, how can I change a pin one by one?



Your help will be appreciated.

Mike Green

1) Unless the 7 Pings are in completely different spaces (rooms, boxes, etc.), you should not use them at the same time. The sound pulses from one will be received by the others and will confuse them. You can use them one at a time allowing the sound echos to die out before going on to the next one.

2) Each Ping is attached to a different I/O pin. You will need a subroutine for each one that sets the I/O pin to output, generates the trigger pulse, sets the I/O pin to input, initializes the timer to count down (or up), waits for the leading edge of the pulse from the Ping, starts the timer, waits for the trailing edge of the pulse, reads the timer value, and disables the timer.

This is not a PIC support forum, so you are unlikely to get much help in specifically writing the PIC code, but the same general principles apply whether you use a PIC or a Propeller or an SX to control a bunch of Pings.

Chris Savage

Your duplicate post in the Robotics Forum was removed.

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Chris Savage
Parallax Engineering

Oldbitcollector (Jeff)

Mike Green said...
1) Unless the 7 Pings are in completely different spaces (rooms, boxes, etc.), you should not use them at the same time. The sound pulses from one will be received by the others and will confuse them. You can use them one at a time allowing the sound echos to die out before going on to the next one.

I had honestly considered using multiple PING units for a musical
instrument before reading this. I've noticed in my travels to Parallax
they have a robot which is using three pings. (granted pointed
about 20-30 degrees in different directions)

The signal that comes from the PING is audio/ultrasonic?
Is there another way to use multiple PINGS next to each other or
should I be looking into another sensor.

I was originally envisioning PING sensors about 3 inches apart,
each facing upward. Sounds like this won't work.

OBC

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Mike Green

Sound travels at about 1/3m in 1ms. At the maximum range of the PING, that's 9ms one way or 18ms round trip. If you allow for 2 or 3 round trip times for echos to die down, that's 50-60ms. You could easily cycle through 3 PINGs 3 times a second. You could probably cycle through 7 PINGs twice a second.

Oldbitcollector (Jeff)

Ah, That's more than fast enough for my PING air-piano project!

You've put that project back on the immediate list! Thank you!

OBC

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Visit the: The Propeller Pages @ Warranty Void.