12f675_fuse_about_to_blow!

[LEDave]

HI Henrik

I've looked lookup in the manual (I found a copy on the net, then realised there's one in the demo-program...doh).

So are we saying that to make the seven segment display show a '3' our loop count would be:00000011 '3' but that would LOOKUP a stored value of :%01001111 and display that?

So we'd have to 'load in' somewhere a table of values:

%01001111 3 b3
%01011011 2 b2
%00000110 1 b1
%00111111 0 b0

So:

FOR B0 = 0 TO 3 ' Count from 0 to 3
LOOKUP B0,[%00111111],B1 ' Get character number B0 from string to variable B1
SEROUT 0,N2400,[B1] ' Send character in B1 to Pin0 serially
NEXT B0 ' Do next character

*Shouldn't SEROUT be something like PAROUT (parallel out) namely display all seven bits on seven pins at once.*

Dave (struggling but trying).

[mackrackit]

*Shouldn't SEROUT be something like PAROUT (parallel out) namely display all seven bits on seven pins at once.*

No,
GPIO = B1
will set the bits to whatever B1 is.

SERIOT is for RS232 type stuff.

Another lesson

[LEDave]

Hi mackrackit

"You might get creative and shift the bits 4 four places.
Lower four to one port, upper four to the other???"

How difficult is getting creative for a newbie like me?

My PICkit1 came with a PIC16F684 included.

Dave

[rmteo]

The '<<' and '>>' operators shift a value left or right, respectively, 0 to 15 times. The newly shifted-in bits are set to 0.

B0 = B0 << 3 ‘ Shifts B0 left 3 places, (same as multiply by 8)
W1 = W0 >> 1 ‘ Shifts W0 right 1 position and places result in W1 (same as divide by 2)

[HenrikOlsson]

Hi,
SEROUT is for serial RS232 communication. It's just used as an example in the LOOKUP section of the manual.

i VAR BYTE
Main:
  For i = 0 to 9
   LOOKUP i, [0, 6, 91, 79, 102, 109, 125, 7, 127, 103], GPIO
   Pause 500
  Next
Goto Main

See, when i is 0 the first value in the lookup table (0) will get written to GPIO, all bits will be reset, when i is 6 the seventh value (125) in the lookup table will get written to GPIO. 125 is the same as %01111101 which means all segments except the one driven by Bit1 will be on - the display will show "6".

Now, this would work on a PIC with seven or more consecutive GPIO pins, which apparently doesn't exist.... Getting a PIC with a "full" PortB and using that instead of GPIO would do it. It's still possible to do on the '684 (which has 6 bits on PortA and 6 bits on PortB, no GPIO) but then maby the Lookup aproach isn't the most suitable.

There are many many ways to skin the cat, sit down and play a bit with what you have, if you already have the BCD-Seven segment decoder go ahead and use that and play around.

/Henrik.

[mackrackit]

In the Math Operators section of the manual take a look at SHIFT and the Btiwise Operators.

The idea is..
From Henrik

To display a "2" you need to set bits 0, 1, 3, 4 and 6 (%01011011 or 91)

You will have to connect the display so that part is on one port and part on another. half and half...
Take the lower 4 bits in the case of #2 (1011) and send them to the display with Port1.
Take the upper 4 bits (0101) and send that to the display with Port2.

Think of Port1 as being 0-3
Port2 as 4-7

Presto... a whole Port...0-7

[LEDave]

Well plenty to think about today. Maybe a little consolidation from me, drum those basics into my mind (I still have plenty to learn here).

I see what you're saying regards splitting port1 & port1 to drive the display.

Absolutely fascinating stuff though, I think I'm hooked and I've only managed to flash a few LED's.

Again many thanks to you all.

Dave

[LEDave]

Hi everyone. I've been working on a program below which is a modification of Henrik's look up table program. I know if you had a PIC with an eight bit wide output you could store the output words in the lookup table and then drive a seven segment display directly as Henrik explained.

So I thought I'd try and load a lookup table to blink an LED (D0) 3 times using a for-next-loop (I've never used a for-next-loop before). It works except after three cycles it doesn't stop. I read up that after the loop has finished it then moves on down to the next instruction, so I've added STOP / END. IF i = 4 then STOP. None of these work and when any of these lines are added the program only cycles once.

The only thing I can think of is that the 12F683 doesn't support LOOKUP tables.

Any ideas please? Dave

ANSEL = %00000000 'disable analog select so ports work as digital i/o
CMCON0 = %00000111 'Disable analog comparators
TRISIO = %11001111 'Set GPIO.4&5 to input
GPIO = %00000000 ' set all outputs low

i VAR BYTE

START
Main:
pause 500 'pause 500 mili-secs
For i = 1 to 3 ' loop count variable (value i) also number of times to loop.
LOOKUP i, [ 223, 223, 223] ,GPIO '223 = %11011111 D0 switches on (GPIO.4)
Pause 500 'pause 500 mili-secs
LOW GPIO.4 ' DO switches off
Next i ' loop again. ONE is added to count i and prog jumps to FOR

[Acetronics2]

Hi,

I read "somewhere" a program might end by the " END " directive, or loop to a known label in the program...

Alain

[rmteo]

Dave, use <code> tags and format your code - makes it easier to read.

ANSEL  = %00000000 'disable analog select so ports work as digital i/o
CMCON0 = %00000111 'Disable analog comparators
TRISIO = %11001111 'Set GPIO.4&5 to input
GPIO   = %00000000 ' set all outputs low

i VAR BYTE

START
Main:
pause 500          'pause 500 mili-secs
For i = 1 to 3     ' loop count variable (value i) also number of times to loop.
  LOOKUP i, [ 223, 223, 223] ,GPIO      '223 = %11011111 D0 switches on (GPIO.4)
  Pause 500        'pause 500 mili-secs
  LOW GPIO.4       ' DO switches off
Next i             ' loop again. ONE is added to count i and prog jumps to FOR