Simulation for 16F877A works fine at 20 Mhz but not on 4MHz

[XMAXY123]

Hi,
Can anyone please help?

Iam using Proton IDE to program and ISIS to simulate.

Hi, its great to see you visiting our forum. Why not try Proton Compiler for FREE? Download the FREE version of Proton Compiler, Its called Amicus18 and its available from HERE Already using proton Compiler??? Get rid of these pesky messages... get LICENSED USER STATUS

The PIC is I propose to use is 16F877A running at 4MHz
simulation is fine and program works OK on both 4 and 20MHz
with the exception of:
HRSOut "Hello World"
which when on 20MHz send it perfectly to the virtual terminal but when on 4MHz shows rubish on the terminal.
The fact that it works fine on 20MHz seem to indicate that all configuration settings are ok
The processor clock frequency in the ISIS simulator is set to 4 or 20 Mhz as appropriate to co-incide with the Xtal setting in the program
Anyone any idea as to the problem
Thank you for your interest.

[RGV250]

Hi,
It sounds like you have a config setting incorrect, probably the OSC so try OSC = HS for 20mhz and OSC = XT for 4.
ISIS is not so picky for those settings.

Regards,
Bob

[XMAXY123]

Hi RGV250,
Many thanks for ur reply.
Pse see comments on Labcentre ISIS forum. I have checked their solution and it works
Hope this is useful
Regards

[Les]

It would have been more useful if a link had been placed to the relevant Labcentre forum section.

[Lester]

Hi User XMAXY123, if you complete the form here, we can update your status on the forum to licensed user.

_{Note: only forum users that do not have Licensed user status can see and complete the form.}