pic16f876 20mhz resonator

[n.mirzai]

Can anyone help
I am using PIC16F876 20 MHZ chip, it works with 8MHZ resonator but not with 20MHZ, your help is apperciated

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[captainslarty]

Hi Sir,
resonator or xtal ?
also sample code for setup would be appreciated.then maybe someone can help.

[n.mirzai]

hi,
Thanks for your help. as I said it works with 8MHZ but not with 20MHZ, ucontroller is 20MHZ device.
using resonator:
sample code:

Device = 16F876
XTAL = 20
ALL_DIGITAL = TRUE ' Set PORTA to all digital for optical use only

TRISB = %00011111 ' PortB RSIN, B2,B3,enb
TRISC = %00000000 ' PortC as output to LCD
TRISA = %011111 'port A.0 A.1 A.2 A.3 A.4 as input A.5 output
' Graphic LCD pin Assignments
Declare LCD_DTPORT PORTC 'portC is used for LCD data
Declare LCD_ENPIN PORTB.3 'Enable LCD
Declare LCD_RSPIN PORTB.2 'RS for LCD
Declare LCD_INTERFACE 8 '8Bit system lcd
LCD_LINES = 2 'four line display
LCD_TYPE = 0

DelayMS 300 ' device to settle down
' Define program variables

Dim ratio As Byte
Dim inpulse As Byte
'*********** Start **********
ratio = 0
inpulse =0
main:
GoSub setratio
Print At 1,1,"Freq Divider"
Print At 2,1, "Ratio = ",@ratio

start:
If PORTB.1 &1<>1 Then GoTo start
start1:
If PORTB.1 &1<>1 Then GoTo start1
checkagain:
If PORTB.1 &1=1 Then GoTo checkagain
inpulse =inpulse +1
If inpulse<ratio Then GoTo start1
High PORTB.5
DelayUS 1 ' to be decided by user soon
Low PORTB.5
inpulse =0
GoTo start1
'**** Set ratio ******
setratio:
Cls
Print At 1, 1, "Set Ratio "
Print At 2, 1, " OK"
'********* ok acknowledged here **********
GoSub okbut:
'********************* Inc ratio ***********************
increst:
Cls
ratio = ratio + 1
If ratio>250 Then ratio=1

Print At 1, 1, " Ratio = ", @ratio
Print At 2, 1, " OK OR INC"
If PORTB.0 &1 =1 Then GoSub incbut
DelayMS 70
If PORTB.4 &1=1 Then GoSub okbut
final:
If PORTB.0 &1 = 1 Then GoTo increst
DelayMS 70
If PORTB.4 &1 <> 1 Then GoTo final:
GoSub okbut
DelayMS 50
Cls
Return ' return for setratio

'**************** Inc But ************************
incbut:
If PORTB.0 &1 <> 1 Then GoTo incbut
DelayMS 70
inc2:
If PORTB.0 &1 = 1 Then GoTo inc2
DelayMS 70
If PORTB.0 &1 = 1 Then GoTo inc2
DelayMS 70
Return
' **************** OK BUT ************************
okbut:
If PORTB.4 &1 <> 1 Then GoTo okbut
DelayMS 80 'Debounce
okbut1:
If PORTB.4 &1 = 1 Then GoTo okbut1:
DelayMS 80
If PORTB.4 &1 = 1 Then GoTo okbut1:
DelayMS 80
Return

[captainslarty]

Hello N.Mirzai
you need to set the config fuses.
Download Fuse configurator from wiki - also check the datasheet for fuse (config) values -

[n.mirzai]

Hello,
I tried wiki , could not down load as asking for user name /password. I tried my proton forum's user name /password did not accept. how do i register for downlaod .
Thanks

[teo]

username : protonuser
password : forumfiles
Teo

[n.mirzai]

Thanks i will try it.

[n.mirzai]

Hi I tried it and it added this:
Config CP_OFF, DEBUG_OFF, WRT_ENABLE_ON, CPD_OFF, LVP_OFF, BODEN_OFF, PWRTE_OFF, WDT_OFF, XT_OSC
to my program when selected the microcontoller, still the same.no charactor on the display,
any advice ? thanks

[pic-ignorant]

Try changing XT_OSC to HS_OSC

John

[n.mirzai]

Thanks for your help, I am using resonator rather than xtal , as I said it works with 8mhz not 20, pic is 20mhz decice.
I have:
Config HS_OSC,WDT_ON,PWRTE_ON,BODEN_ON,LVP_OFF still not working,
any idea.
Thanks