Ping my LED
crazyrobotgirl
Posts: 32
Hello all. I am alittle stuck trying to get my LED on pin 7 to turn on when my ping senser is reading < than '90, and turn off when => '90.
{{
┌─────────────────────────────────────┬────────────────┬─────────────────────┬───────────────┐
│ dualPing Demo │ BR │ (C)2008 │ 13Sept09 │
├─────────────────────────────────────┴────────────────┴─────────────────────┴───────────────┤
│ │
│ Update/extension of the original Savage/Martin object. │
│ This object is a dual-channel driver for Ping))) ultrasonic ranging units (Channels A & B).│
│ A single cog is used to monitor both ping units (via counters A & B). │
│ │
│ Features: •counters used for time-of-flight measurement (fire & forget) │
│ •dual ping driver capable of 2 simultaneous measurements │
│ •simple ambient temperature compensation functionality │
│ •drop-in replacement for original object │
│ │
│ Miscellaneous notes: │
│ •Although this object can drive 2 Ping))) units, it works perfectly fine for single │
│ channel applications, too...just leave the AorB selector set to A and use channel A. │
│ •If you are using two Ping))) units simultaneously, there is significant possibility │
│ for mutual interference. To avoid this, it is recommended that the two Ping))) units │
│ be placed AT LEAST a foot apart and that each be angled at least 15-20 deg out from each │
│ other. │
│ •It is strongly recommended that the Ping))) units be mounted inside small open-ended │
│ boxes (like project boxes, for example) to help isolate them from noise. Why? │
│ A room is typically a confined space filled with many hard surfaces and lots of good │
│ sound reflectors that tend to accentuate noise. In addition, the Ping))) unit apparently │
│ has significant ringdown and/or sidelobes that can add to this interference. As such, │
│ it can sometimes be difficult to get consistent/reliable range measurements. A box helps │
│ to: a) block extraneous ambeint noise b) channel energy coming from sidelobes out toward │
│ the front of the sensor where it does no harm, and c) adds directivity to the reciever. │
│ For example: the back wall of my garage is made of cinder blocks. If the bare Ping))) │
│ unit is placed against this wall facing out into the garage, I cannot get a correct range │
│ measurement as long as the Ping))) unit is within about 8" or less of this block wall, │
│ presumably because energy from sidelobes bounces off the many scatterers in the rough │
│ surface of the cinder blocks. If the Ping))) unit is placed in a small box, the unit │
│ can be mounted against the wall without trouble. Chris' installation appears to be │
│ optimal: [URL]http://forums.parallax.com/forums/default.aspx?f=21&m=176721[/URL] │
│ •A note on temperature compensation...a temperature variation of 0 deg F to 100 deg F will │
│ change the resultant distance measurement by √(560/460) or ~10%...not a big deal in most │
│ applications, but perhaps worth considering for those cases where a considerable range │
│ of ambient temperature is expected. │
│ │
│ See end of file for terms of use. │
└────────────────────────────────────────────────────────────────────────────────────────────┘
SCHEMATIC
───────────────────────────────
2X: ┌───────────────────┐
│┌───┐ ┌───┐│
││ ‣ │ PING))) │ ‣ ││
│└───┘ └───┘│
│ GND +5V SIG │
└─────┬───┬───┬─────┘
│ │  1K
 └┘ └ to Prop
───────────────────────────────
}}
CON
_clkmode = xtal1 + pll16x ' System clock → 80 MHz
_xinfreq = 5_000_000
'hardware constants
pingA = 9 'pin-- ping))) A
pingB = 8 'pin-- ping))) B
'software constants
updaterate = 8 'range update rate when active (measurement cycles per second) ~15 max
'machine states
#0, a, b
VAR
OBJ
debug: "SerialMirror" 'Same as fullDuplexSerial, but can also call from subroutines
ping: "dualPing" 'Updated ping object (dual channel fire & forget)
PUB Init
waitcnt(clkfreq * 5 + cnt) 'Start FullDuplexSerial
Debug.start(31, 30, 0, 57600)
Debug.Str(String("MSG,Initializing...",13)) 'Note: debug formatting is set up for use with plx-daq
ping.calibrate(68) 'calibrate ping for ambient temperature=68 F
main
Pub Main| mark, distA, distB
mark := cnt 'process initialization time
dira[1] :=1
repeat
ping.selectAB(a) 'Select channel A
distA := ping.ReadPingIn 'read Ping))) channel A
' distA := ping.ReadPingTenths
ping.fireping(pingA) 'restart measurement cycle on channel A
ping.selectAB(b) 'Select channel B
distB := ping.ReadPingIn 'read Ping))) channel B
' distB := ping.ReadPingTenths
ping.fireping(pingB) 'restart measurement cycle on channel B
'Now have two new measurement values and have restarted the Ping))) measurement cycle...
'Cog is free to do other things while the next measurement cycle is runnning...
distA := kalman1c(distA,0) 'Mild filtering to supress msmnt jitter
distB := kalman1c(distB,b) 'Mild filtering to supress msmnt jitter
Debug.Str(String("DATA, TIME, TIMER, "))
Debug.Str(String(" distA, ")) 'kick out measurement data for display
Debug.Dec(distA)
Debug.Str(String(" distB, "))
Debug.dec(distB)
Debug.Str(String(13))
mark += clkfreq/updaterate
waitcnt(mark)
'wait for next measurement frame
[COLOR=#FF0000]Pub ReadPing| mark, distA, distB
dira[7]:=1 'LED on pin 1
repeat
if distB => 90
outa[7] :=0
if distB < 90
outa[7] :=1
mark += clkfreq/updaterate
waitcnt(mark)
[/COLOR]
pri kalman1c(x_meas,AorB):x_ret
''Simple 1-D kalman filter for scalar random constant with simplified covariance model.
''Uses a constant covariance (and therefore hard-coded kalman gain). Simplifies/speeds
''up calculations. User must manually select gain, where gain is given by:
''gain = const / k_scale (high gainbelieve msmnts)
''Max filter update rate ~9000 samples/sec for 1 cog @ clkfreq=80
'Note: as implemented here, this is actually 2 filters, one for channel A and one for B
'Can easily delete the AorB functionality if only a single channel is desired
x_prev[AorB] := x_cur[AorB]
x_cur[AorB] := (x_prev[AorB] * k_scale + (k * (x_meas - x_prev[AorB]))) / k_scale
' Debug.Str(String(" x_meas, "))
' Debug.dec(x_meas)
' Debug.Str(String(" x_prev, "))
' Debug.Dec(x_prev[AorB])
' Debug.Str(String(" x_cur, "))
' Debug.dec(x_cur[AorB])
return x_cur[AorB]
dat
'-----------[ Predefined variables and constants ]-----------------------------
k_scale long 65_536 '2^16 (scaling varible on K, needed because K is of order 1)
k long 32_768 'Kalman filter gain, in this case 32_768 / 65_536 = 0.5
x_prev long 0,0 'Kalman filter estimate of x at previous timestep
x_cur long 0,0 'Kalman filter estimate of x at current timestep
DAT
{{
┌─────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ TERMS OF USE: MIT License │
├─────────────────────────────────────────────────────────────────────────────────────────────────────┤
│Permission is hereby granted, free of charge, to any person obtaining a copy of this software and │
│associated documentation files (the "Software"), to deal in the Software without restriction, │
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│and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,│
│subject to the following conditions: │
│ │ │
│The above copyright notice and this permission notice shall be included in all copies or substantial │
│portions of the Software. │
│ │ │
│THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT│
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│IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────┘
}}
Comments
You also have a local "ReadPing" method that you are not calling from anywhere. So your tests against 90 are never happening.