input register (INA) to variable

PJAllen · 2011-05-16 10:46

I think I'm not understanding the Propeller Manual.
If I have a pushbutton to P8...

dira[8] = 0

byte  btnstatus

btnstatus := ina[8]

If ina[8] is HI then btnstatus = %0000 0001 ?
Or do I have to make btnstatus a long and then btnstatus would be %...0000_0001 0000_0000 ?

Mike Green · 2011-05-16 10:54

INA[ 8 ] extracts bit #8 to yield a single bit value (0 or 1), so btnstatus is 1 when I/O pin #8 is high.

In general, INA[ x..y ] extracts a bit field whose high order bit is x and whose low order bit is y. If y > x, then the bits are in reversed order from how they're represented as I/O pins. In all cases, this bit field is right justified in a 32 bit value.

PJAllen · 2011-05-16 11:32

OK.

I have:
dira[15..0] := $00FF (So 15..8 are INs, 7..0 are OUTs)

Going the btnstatus/alias route resulted in anxiety.
When I test ina[8] directly, it's as I expect, 0/1, and things move along.

I should grab a shovel and move everything closer to the computer instead of going back and forth across "the office" as I am.

Ariba · 2011-05-16 13:09

PJ Allen wrote: »

...Or do I have to make btnstatus a long and then btnstatus would be %...0000_0001 0000_0000 ?

Yes, this is also possible:

long  btnstatus

btnstatus := ina

now every bit in btnstatus represents the corresponding input pin.

Andy

PJAllen · 2011-05-16 14:20

OK.
The objective is for a pushbutton (Jog) to advance a stepper position.
In buttonchecking2.spin, I test ina[8].
In buttonchecking3.spin, I test 'btnstatus'.

PUB buttoncheck
  repeat until ina[8] == 1
  position := position + 1

versus

PUB buttoncheck
  repeat until btnstatus == 1
    btnstatus := ina[8]       ' stays stuck w/o
  userpause                   ' dbl-clicks w/o
  btnstatus := ina[8]         ' goes automatic w/o
  position := position + 1

Both work, but the second version (buttonchecking3) takes more lines of code or it'll double-pulse.
Where am I going wrong?

PJAllen · 2011-05-17 08:13

Some D/L'ers, I see, but no replies.
That's OK. It's only about Spin and things Propeller, not some supercilious ancillary pretense at association with one.
Oh well.
Such is the Propeller Forum Echo Chamber.

I still found what I was looking for, within me, applying the gray matter, as ever. If anyone's interested, see #9 over here.

schill · 2011-05-17 08:45

This is not exactly an answer to your problem, but rather a question about your code. By the way, I'm not sure exactly what's happening, but the problem sounds like a debounce issue (but the delays you've thrown in should be minimizing that, I think).

Anyway, I was wondering why you didn't write the second version like this:

PUB buttoncheck
  btnstatus := ina[8]
  repeat until btnstatus == 1
    btnstatus := ina[8]     
  userpause                   
  position := position + 1

The basic structure should be the same as your first version. If you use the following, does it work?

PUB buttoncheck
  btnstatus := ina[8]
  repeat until btnstatus == 1
    btnstatus := ina[8]     
  position := position + 1

I know you say you've already solved your problem (by changing the overall structure of the code) but I'm curious about what the issue here is.

input register (INA) to variable

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