Random number -> Corresponding LED lit (n00besque content contained)

[Darrel Taylor]

LED1 = !(MyByte != 1)
LED2 = !(MyByte != 2)
LED3 = !(MyByte != 3)
LED4 = !(MyByte != 4)
LED5 = !(MyByte != 5)
LED6 = !(MyByte != 6)

[HankMcSpank]

LED1 = !(MyByte != 1)
LED2 = !(MyByte != 2)
LED3 = !(MyByte != 3)
LED4 = !(MyByte != 4)
LED5 = !(MyByte != 5)
LED6 = !(MyByte != 6)

Excellent, the top of my fishing rod is moving a touch!

but I don't understand the response!

eg if the random number comes out as 1, meaning I want to light LED1.....normally - if wanting to light LED1 for 200ms, I'd simply do this....

HIGH LED1
PAUSE 200
LOW LED1
PAUSE 200

but, how do I do this......

HIGH LED'result_of_random_number'
PAUSE 200
LOW LED'result_of_random_number'
PAUSE 200

Apologies if that is what you just told me Darrel, but I'm not sure how to use the info you gave me (that'll be the n00bishness that's never far away from all I do!)

[Darrel Taylor]

Change the conditions on me eh ...

How about ...

;---------------------------------------
Main:
    Random MyWord
    MyByte=(MyWord//6)+1
    GOSUB HIGH_LED
    PAUSE 200
    GOSUB LOW_LED
    PAUSE 200
GOTO Main
;---------------------------------------
 
HIGH_LED:
  SELECT CASE MyByte
    CASE 1 : HIGH LED1
    CASE 2 : HIGH LED2
    CASE 3 : HIGH LED3
    CASE 4 : HIGH LED4
    CASE 5 : HIGH LED5
    CASE 6 : HIGH LED6
  END SELECT
RETURN
 
;---------------------------------------
LOW_LED:
  SELECT CASE MyByte
    CASE 1 : LOW LED1
    CASE 2 : LOW LED2
    CASE 3 : LOW LED3
    CASE 4 : LOW LED4
    CASE 5 : LOW LED5
    CASE 6 : LOW LED6
  END SELECT
RETURN

[HankMcSpank]

Hey Darrel...that works a treat ...I've now got pretty twinkly Blue leds randomly flashing before my eyes (which strangely, makes me feel warm inside).

I note that a fair few of the random numbers are the same as the previous (I guess when you've only six to choose from, then that's bound to happen!), so I'll sit down for a few weeks & try & code this out!

Many thanks!

Hank.

Edit: Actually, dialing out the successive repeats only took a couple of minutes...

MyWord var Word
MyByte var Byte
previous_random var Byte
;---------------------------------------
Main:
    Random MyWord
    MyByte=(MyWord//6)+1
    if previous_random = MyByte then goto Main
    GOSUB HIGH_LED
    PAUSE 50
    GOSUB LOW_LED
    PAUSE 50
    previous_random = MyByte
GOTO Main
;---------------------------------------
 
HIGH_LED:
  SELECT CASE MyByte
    CASE 1 : HIGH LED1
    CASE 2 : HIGH LED2
    CASE 3 : HIGH LED3
    CASE 4 : HIGH LED4
    CASE 5 : HIGH LED5
    CASE 6 : HIGH LED6
  END SELECT
RETURN
 
;---------------------------------------
LOW_LED:
  SELECT CASE MyByte
    CASE 1 : LOW LED1
    CASE 2 : LOW LED2
    CASE 3 : LOW LED3
    CASE 4 : LOW LED4
    CASE 5 : LOW LED5
    CASE 6 : LOW LED6
  END SELECT

[HankMcSpank]

Just had a sleep on this - I've never previously used case, and now I fresh look at it, to my eyes it's just a load of IFs?

For example....

HIGH_LED:
  SELECT CASE MyByte
    CASE 1 : HIGH LED1
    CASE 2 : HIGH LED2
    CASE 3 : HIGH LED3
    CASE 4 : HIGH LED4
    CASE 5 : HIGH LED5
    CASE 6 : HIGH LED6
  END SELECT
RETURN

could be written as...

IF MYBYTE = 1 THEN HIGH LED1
IF MYBYTE = 2 THEN HIGH LED2
IF MYBYTE = 3 THEN HIGH LED3
IF MYBYTE = 4 THEN HIGH LED4
IF MYBYTE = 5 THEN HIGH LED5
IF MYBYTE = 6 THEN HIGH LED6

So when to use case & when to use if?

Going back 20 years to when I used to write simple VMS DCL programs, I could construct code like thus...

HIGH "LED"+'MyByte'

the stuff inbetween " " was text & stuff in the ' ' was the value held in a variable

therefore the above would actually run as.....

HIGH LED1 (assuming MyByte held 1) ......presumably no similar ways of constucting in Picbasic?

[Darrel Taylor]

Select Case is a lot like a "Load of IF's" with a few differences.

1. It removes some of the (n00besque content contained) look and feel.
2. Only the first "CASE" that evaluates TRUE will execute, then it exits the SELECT block.
   In your list of IF's, if the first one is true, it still goes on and evaluates all the other IF's too.
   This allows more complex logic, where more than one test can be true, but only the first one is acted on.

The same functionality using IF statements would look like this ...

IF MYBYTE = 1 THEN
    HIGH LED1
ELSE
    IF MYBYTE = 2 THEN
        HIGH LED2
    ELSE
        IF MYBYTE = 3 THEN
            HIGH LED3
        ELSE
            IF MYBYTE = 4 THEN
                HIGH LED4
            ELSE
                IF MYBYTE = 5 THEN
                    HIGH LED5
                ELSE
                    IF MYBYTE = 6 THEN
                        HIGH LED6
                    ENDIF
                ENDIF
            ENDIF
        ENDIF
    ENDIF
ENDIF

OR, if you have PBP 2.60 you could do it like this ...

IF MYBYTE = 1 THEN 
    HIGH LED1
ELSEIF MYBYTE = 2 THEN 
    HIGH LED2
ELSEIF MYBYTE = 3 THEN 
    HIGH LED3
ELSEIF MYBYTE = 4 THEN 
    HIGH LED4
ELSEIF MYBYTE = 5 THEN 
    HIGH LED5
ELSEIF MYBYTE = 6 THEN 
    HIGH LED6
ENDIF

It may not seem like much difference with this simple example, but with large SELECT CASE blocks using more complex comparisons, it can save a boat load of execution time not having to evaluate every condition.

* SELECT CASE is also much easier to read. Especially when it's not your program.

PicBasic Pro, was written to generate the Smallest and Fastest code possible. As it is the HIGH/LOW statements only use a couple of instruction cycles. If you add in the abilities to use them like array's and access pins non-contiguously, it would make EVERY HIGH/LOW statement Bigger and Slower, breaking everyone's code, and causing more complaints than not having those abilities produces.

[HankMcSpank]

Many thanks Darrel....crystal clear now