correct setup_adc() when using 4x PLL???

davefromnj · Joined: 03 May 2007 Posts: 42

Hello all,

I'm using an 18F65J10 with a 4MHz ceramic resonator. I would like to use the 4X PLL multiplier so that the PIC executes code at 16MHz internally.

I would also like my A to D's to work properly...

I seem to be having great difficulty in finding the right combination of constants to pass to the setup_adc() function:

setup_adc(ADC_CLOCK_DIV_16|ADC_TAD_MUL_16);

definitely doesn't seem to be working properly:

Can someone help me out with the right constants to pass to setup_adc ?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

kevcon · Joined: 21 Feb 2007 Posts: 142 Location: Michigan, USA

If you are using version 4 CCS compiler earlier than 4.027 or 4.026( I can't remember which ) the PLL enable code that the compiler generated did not work and you had to set it manually.

davefromnj · Joined: 03 May 2007 Posts: 42

Hello,

Thank you very much for that update...

I'm currently using 4.023, so this sounds about right.... I'm having major timing issues when the PLL is enabled, and they only get crazier when I mess with the setup_adc(null,null) constants.

I have the pic reading adc values, and also sending out a duty cycle 0.5second on, 0.5second off pattern, based on timer0 expiring every 1ms.

When I mess with the setup_adc() constants, the output timing gets really screwed up--sometimes it goes too fast, sometimes too slow.

kevcon · Joined: 21 Feb 2007 Posts: 142 Location: Michigan, USA

You should really get the latest version, there are a lot of bug fixes between 4.023 and 4.034.

davefromnj · Joined: 03 May 2007 Posts: 42

kevcon · Joined: 21 Feb 2007 Posts: 142 Location: Michigan, USA

http://www.ccsinfo.com/devices.php?page=versioninfo

This list is far from complete, it doesn't show the bugs I have reported and are fixed, the PLL bug for one. And I'm sure there are many more that have been fixed that aren't included.