Railway Traverser

[jamesrj]

Hello Forum.
Can you help an oldboy new to the picaxe world??
Years ago I constructed a railway traverser, which carried 4 tracks, powered by a DC motor driving a screwed rod, a limit switch at the ends changed over the direction via relays, and using just 1 push to make switch in the control circuit ( like a two way lighting circuit). Motor turns were counted by a hard wired up/down counter some logic
via an opto switch on the shaft. Every push of the button would move the table 1 track at a time,stop after a preset count.
Now with the aid of a picaxe 18x, 2 *12v Bipolar steppers (Rapid) working in tandam each with its own driver chip.
I am using the codes from the manual,but, I am having a problem remembering my Basic ( ZX81 )!!!of how I can use that 1 push button to make the table reverse after it has reached the 4th track, (lstep and on the 7th push to (rstep
(ie: every 3rd push of the button would reverse the table ). ( No problem with 2 buttons 1 for each direction.)
The distances between tracks are the same so I can enter the same 2 byte variable code w0.
Would it be some kind of count code with goto's, but I can't see it..
Thank you in advance if you can put me on the right track. no pun intended..................rj

 

[hwholmes]

( No problem with 2 buttons 1 for each direction.)
.....Would it be some kind of count code with goto's, but I can't see it..

If you have the code for two push buttons then all you need is to determine where you are in the count sequence.

If you use a MOD 6 (ring) counter:

cnt = cnt + 1 % 6

then cnt will go from 0 to 5 and repeat 0....5,0,...5,0 etc.

Now decide if cnt >= 3.

False use code for one direction (as if using that push button) and True goes the other way.

Note: check the direction before incrementing the counter.

 

[jamesrj]

Thanks for your reply,but as a newbe where would I find this info in the manual
Mod6 (ring) counter, is there any other way??
Like the tag..
rj

 

[nick12ab]

Thanks for your reply,but as a newbe where would I find this info in the manual
Mod6 (ring) counter, is there any other way??
Like the tag..
rj

Look under Variables - Mathematics in PICAXE Manual 2.

 

[hwholmes]

Mod6 (ring) counter, is there any other way??

This has the same effect as:

cnt = cnt + 1
if cnt = 6 then
  cnt = 0
endif

Which may be easier for someone who is not familiar with the MOD (also sometimes called remainder) operator.