Instant Interrupts - Revisited

[Darrel Taylor]

Yup, that's pretty slow.

At 20mhz with 1:1 prescaler, you'll get an interrupt every 13.1ms.
That's 52.4ms for all 4 digits, which is a 20hz refresh rate. Way too slow.

If you want to make it go faster, you have to load something in the Timer. As it is, it's just free-running.

Also, you'll never get those SERIN/OUT2's to work. They are timed by software, which gets continuously interrupted. You need to use the USART with HSERIN/OUT.

And, ENABLE/DISABLE are for ON INTERRUPT. They have no effect with Instant Interrupts.
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[itelmex]

Darrel, thanks. before your instant interrups tools never I was experimenting interrupts.

I have clear idea the hserin/hserout sustitution, but I ignored what's the procedure (concretly) for incress the speed.

I havew the display working now, but I need to find de solution for the slow scan.

The question is How incress the speed with the preescaler 1:1 now?

what's the value for load?

Thanks and regards

Luis Elizarraraz

[Darrel Taylor]

The question is How incress the speed with the preescaler 1:1 now?

what's the value for load?

You should have at least 100hz refresh rate, or 400hz interrupts (4 digits).

DEFINE  Freq 400
DEFINE  Prescaler 1
Timer1  VAR WORD EXT
TmrLoad CON EXT
@Timer1 = TMR1L
@TmrLoad = 65536 - (OSC*1000000/4/Prescaler/Freq)

Then, first thing in the handler...

T1CON.0 = 0
Timer1 = Timer1 + TmrLoad
T1CON.0 = 1

[itelmex]

Darrel:

Thanks for the solution!

For finish this project, I'm going to show the final version for the code.

Recapitulation:

Hardware:

Four 7 segments modules conected to the portb, like driver using uln2803.

Each module is conected to the anode with 2 transistors: bc337 directed to portd (portd.4 to portd.7 for each module) and from the bc337 colector to the irf640 gate.

For the communication, max232 connected to the pc (data inputs) and the ttl side, to the portc.6 and portc.7 (tx and rx).

I send to the pc the characters "C>" like invitation for to introduce the data.

The data follow the format: "CXXXX" where XXXX is any number from 0000 to 9999.
When the circuit receive the data in the correct format, this send to the pc the character "L" (Listen).

The problems with the slow scan was solutioned with the Darrel Taylor instant interrups tools. I finded relative easy the first project using interrups..!Thanks and more thanks Darrel ¡

Finally, the code:


'-----------------------------------program picbasic pro /Darrel support-------------------
'
INCLUDE "MODEDEFS.BAS"

define loader_used 1
DEFINE OSC 20

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_BAUD 9600
'DEFINE HSER_SPBRG 25

DEFINE Freq 400
DEFINE Prescaler 1
Timer1 VAR WORD EXT
TmrLoad CON EXT
@Timer1 = TMR1L
@TmrLoad = 65536 - (OSC*1000000/4/Prescaler/Freq)


INCLUDE "DT_INTS-18.bas" ' Base Interrupt System
INCLUDE "ReEnterPBP-18.bas" ' Include if using PBP interrupts


' ** Declare the Variables **
LEDS Var Byte ' The amount of LEDs in the display
O_C Var Byte ' Used by the interrupt for time sharing
Counter Var byte ' General purpose counter
Del Var Word ' General purpose delay loop variable
del1 var word
D_Number Var word ' The number to display on the LEDS
DP Var Byte ' Position of the decimal point
Disp_Patt Var Byte ' Pattern to output to PortC
Num Var Byte[4] ' Array to hold each digits value

TRISD=%00001111 'portd.4 a portd.7 como salidas
TrisB=0 ' Make PortB and PortC outputs
PortC=0:PortB=0 ' Clear PortB and PortC
O_C=0 ' Clear the time share variable

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
INT_Handler TMR1_INT, _Multi, PBP, yes
endm
INT_CREATE ; Creates the interrupt processor
ENDASM

T1CON=$01 ; Prescaler = 8, TMR1ON
@ INT_ENABLE TMR1_INT ; enable Timer 1 interrupts

PORTD=%11110000

Main:
hserout [13,"C>"]
hserin [dec4 D_Number]
SIGUE:
hserout ["L"]
Gosub Display ' Display the value
goto main

Display:
For LEDS=3 to 0 step -1 ' Loop for 4 digits (0-65535) ' Disable the interrupt while we calculate
Num[LEDS]=D_Number dig LEDS ' Extract the seperate digits into the array
If D_Number<10 and LEDS=1 then Num[LEDS]=10 ' Zero Suppression for the second digit
If D_Number<100 and LEDS=2 then Num[LEDS]=10 ' Zero Suppression for the Third digit
If D_Number<1000 and LEDS=3 then Num[LEDS]=10 ' Zero Suppression for the Third digit ' Re-enable the interrupt
Next
return
' INTERRUPT HANDLER
' Multiplexes the 4-digits
'
Multi:
T1CON.0 = 0
Timer1 = Timer1 + TmrLoad
T1CON.0 = 1

'sigue: ' 0 1 2 3 4 5 6 7 8 9 A B C E F G H I J L N 0 U b c d e f g h i n p q s o u Z
lookup Num[O_C],[63,6,91,79,102,109,125,39,127,111,119,127,57,121,1 13,125,118,6,30,56,55,63,62,124,88,94,123,113,111, 116,4,84,115,103,109,92,28,255],Disp_Patt
' Lookup Num[O_C],[192,249,164,176,153,146,130,248,128,144,255],Disp_Patt ' Decode the segments for the LED
' Process the first display (farthest right)
If O_C=0 then portd=%11011111
If O_C=1 then portd=%11101111
If O_C=2 then portd=%01111111
If O_C=3 then portd=%10111111
PortB=Disp_Patt ' Place the digit pattern on portC
O_C=O_C+1 ' Increment the time share counter
If O_C>=4 then O_C=0 ' If it reaches 3 or over then clear it
@ INT_RETURN ' Allow more interrupts
'-----------------------end --------------------------------------------------------

The display is working very good.

Regards.

[Darrel Taylor]

That looks much better.

It's nice to have someone that can take a little guidance, and make it work.

Thanks for the Code Example!