Page 238 - Making PIC Microcontroller Instruments and Controllers

236 U DEtrir DII{GIHECOU IEBS: cou rllc IARBIES

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This simple escapement/nurble chute will be used for all the counting projects with
simple modifications and cha.nges in sensor posltions. Prcvisions should be made for a
bin above and belo\{'the escapemedto acconmdate about a pint ofrnarbles (amund 100).
The alesign should allow the marbles to be rcfiImed to the top bin between runs with
ease so that expodmental counting can prcceed run after run.without delay
For the first gscapemenGbased
counting progam, the oscapement will be prc$arnmed
lo \ ork a. follow(:

l. Ar ltanup. lhe louergale i. closed and lhe uppergate isopen Tbe syslem ensures
this by starthg in this positio[ On reset, go to this position.
2. The counter is set to 0.
3. Load |he marbles.
4. l-f $ere are any marbles in $e sy(tem. fie fiAt marble come\ to rest again\l $e lower
garc'
5.The op!ical detec@ conlrns this.
6. If there is a ma$le above the lower gate, the uppel gate closes.
7. Both gates are closed now.
8. There is a marble b€tween the gates.
9. The lower gate opens and deases the marble.
lO. The counter incremenlsby orc atlhis point.
I I . The lower gate waits 0.01 seconds and closes agail. This makes sure the marble
has dropped away.