Looking for Spin example to look up a value in a list

Don M

I've been messing around with Beau Schwabe's 4x4 keypad demo. It produces a word and depending on which key is pressed sets a bit in the word. The keypad I have has these keys in the order in which I see the bits set (*, 0, #, D, 7, 8, 9, C, 4, 5, 6, B, 1, 2, 3, A). For instance 0100000000000000 would be the "0" key pressed.
How do I iterate through the list to get the corresponding character that aligns with the bit set in the word?

Don M

I got this to work:

VAR
  word  keypad

PUB start | idx
  ' Start PST
  text.start(115200)

  repeat
    keypad := KP.ReadKeyPad 
    repeat idx from 0 to 15
      if (keypad >> idx) == 1
        text.position(5, 2) 
        text.str(@keys[idx])

DAT

  keys  word  "A", "3", "2", "1", "B", "6", "5", "4", "C", "9", "8", "7", "D", "#", "0", "*"

Is there any better or simpler way?

Don M

BTW how do you post code in the forum. I tried [/code] and [\code]...

Wuerfel_21

Triple backticks, like this:.

```
Code goes here
```

Don M

Thanks. I changed it.

Clock Loop

Here is the code!
https://github.com/parallaxinc/propeller/blob/master/libraries/community/p1/All/4x4 Keypad Reader DEMO/4x4 keypad Reader DEMO.spin

You can also use a CASE statement.
Not necessarily better, just easier to read.

And then list all possible states for the keypad

  repeat
    keypad := KP.ReadKeyPad     '<-- One line command to read the 4x4 keypad
    text.str(string($A,5,$B,2))
    text.bin(keypad>>0, 4)      'Display 1st ROW
    text.str(string($A,5,$B,3))
    text.bin(keypad>>4, 4)      'Display 2nd ROW
    text.str(string($A,5,$B,4))
    text.bin(keypad>>8, 4)      'Display 3rd ROW
    text.str(string($A,5,$B,5))
    text.bin(keypad>>12, 4)     'Display 4th ROW
    text.str(string($A,5,$B,9))
    text.bin(keypad, 16)        'Display RAW keypad value

    Case Keypad

       %0100000000000000:     'Zero key pressed.
         Do something

       %0000000000000000:     'No key pressed
         Do something

You can find the correct binary number when you see what the RAW keypad value is on your terminal output.
You can then place that entire binary number into the CASE statement like I did for two of the binary positions.

JonnyMac

How do I iterate through the list to get the corresponding character that aligns with the bit set in the word?

No need to iterate. The >| (encode) operator will tell you which bit is set (+1). This routine will turn your bit into an ASCII character.

dat

  KeyChar       byte    "*0#D789C456B123A"


pub translate_key(keybits)

  if (keybits)
    return KeyChar[>|keybits - 1] 

This will return 0 if no key was pressed, or the ASCII char if one was.

Ariba

Or:

    keypad := KP.ReadKeyPad 
    keychar := lookup( >|keypad : "*0#D789C456B123A")

Don M

Thanks for the help. Much appreciated.