16f1825 Int Osc settings

[chipfryer27]

Hi

Just a quick question.

When trying out a "flash test" (1s on, 1s off) using the above chip on Int Osc, I am getting some serious delay.

With Osc set a 1Mhz the delays are doubled to around 2s
At 4Mhz the delays are around 8s
At 8Mhz the delays are around 16s

I'm guessing I need a block of C-Code at the start as FC might not be able to set the correct registors automatically?

Regards

[Benj]

Hello,

The default speed for the INTOSC on the device is 0.5MHz.

For 1MHz operation the line of C code at the start of your program needs to be

Code: Select all

osccon = 0x58;

For 32MHz operation the line of C code at the start of your program needs to be.

Code: Select all

osccon = 0xF0;

[chipfryer27]

Hi Benj

Thanks for the quick reply.

I am using FC6 and the slowest oscillator setings under Build / General Options is 1Mhz for that chip. I added the C-Code you suggested at the start of my program (but with FC6 still set a 1Mhz) and tried.

The delays now appear to be 100ms or so.

Are the settings in Build / General Options messing things?

Regards

[medelec35]

First you look at the datasheet for the speed you would like internal oscillator to run at e.g 1MHz:

Datasheet osscon.png

(80.88 KiB) Downloaded 1965 times

Then you can follow this post on how to calculate correct osccon value.

Don't forget to set the clock speed in project options e.g 1000000.

If you still stuck then post flowchart.

Martin

[chipfryer27]

Hi Martin

Changed the C-code to 0xd8 and it appears good. I was doing that as you posted. I had read in the datasheet that the default was 500Khz but as FC didn't offer that value it prompted me to ask about the C-code to override the config.

Thanks again you to and Benj
Regards

[kersing]

You can enter your own values for the clock speed by typing the value, the ones offered in the drop down are just often used defaults.

[chipfryer27]

Hi Kersing

Well peel my tangerines.... (to quote Lord Blackadder).

I did not know that.. Doh!

Thanks for that very useful snippet. I thought that as each chip had a drop down, that's what FC imposed. Guess I should really get out less and read more

Thanls again,

Regards

[chipfryer27]

Hi

Deleted the C-code and by directly entering 500Khz under Build etc it still seems to be running well.

Time now to make it do something more useful.

Thanks again to all

Regards