PIC18F25K22 clock problem

[picprogrammer12345]

I am using a PIC18F25K22 chip.
I am using a 20MHz external oscillator.

The fuse setup is as follows:
#fuses HSH,NOPLLEN,NOMCLR,NOWDT,NOLVP,PROTECT,DEBUG //Fuses configuration
#use delay(clock=20000000) //Clock Used is 20 MHz


The software works perfectly fine. But after sometime the code starts to work very slowly.
There is a delay of 3sec in the code before printing information on the LCD. It starts to become a delay of around 15 to 20 second but the software is still working but it is very very slow.
Can someone guide me to right direction on what is happening?

[newguy]

The HSH and HSM fuses are for crystals. For an external oscillator, you need either ECH (external clock, high power) or ECH_IO (same as ECH but your PIC's OSC2 line becomes available for program IO control).

[temtronic]

One possible problem is that the fuse 'debug' is enabled. When enabled, it'll set fuses to what IT wants, not necessarily what YOU need.

Also if using MPLAB, be sure the compile is done in .release' mode not the factory default of 'debug'. Again, that can cause 'fun'.

I also set fuse 'PUT' to enable the 'Power Up Timer' just to help the PIC do 'housekeeping'..

hth
jay

[picprogrammer12345]

The clock I am using is ECS-200-20-46X
Datasheet
http://www.ecsxtal.com/store/pdf/HC-46X.pdf

I think EC would be for a clock that doesnt use both CLKIN pin and LCKOUT pin. But for this I am using both.
Also software is working at first sometimes works for hours. It randomly starts to delay the entire code.

I am using PIC compiler version 4.129 not MPLAB.

[picprogrammer12345]

On the datasheet of PIC18F25K22 for the oscillator and clock it say on page 35:

HS Oscillator mode offers a Medium Power (MP) and a
High Power (HP) option selectable by the FOSC<3:0>
bits. The MP selections are best suited for oscillator
frequencies between 4 MHz and 16 MHz. The HP
selection has the highest gain setting of the internal
inverter-amplifier and is best suited for frequencies
above 16 MHz. HS mode is best suited for resonators
that require a high drive setting.

FIGURE 2-6: QUARTZ CRYSTAL
OPERATION (LP, XT OR
HS MODE)
Note 1: A series resistor (RS) may be required for
quartz crystals with low drive level.
2: The value of RF varies with the Oscillator mode
selected (typically between 2 Mohm to 10 Mohm

If you want to look at the figure please download datasheet. Could it be cause of the resistance? Right now the clock is connected directly to the PIC chip with 22pF caps.

[PCM programmer]

[picprogrammer12345]

[newguy]

For future reference, an oscillator is taken to mean a self contained unit that generates a high stability clock signal on its own. A crystal does not.

Your crystal is a series crystal. That's a problem.

[Ttelmah]

What you have is a crystal, not an oscillator.
A crystal is a 'resonant' device.
A crystal makes an oscillator, when driven by a circuit that amplifies and inverts the signal coming from it's output, and feeds it back to the input.
Yes it uses HSH.
An oscillator is a module that contains the amplifier as well, and just gives a clock output.
You only have an 'oscillator', when connected to the amplifier in the PIC.

I don't think your problem is clock related.

Without seeing your code, it is difficult to have any idea. However something internal in the code, that is sitting waiting for something to happen, and an event (floating pin, or specific signal pattern for example), that changes the wait.

[picprogrammer12345]

Alll the program does is checks analog pin for high voltage. When the adc pin detects high voltage , the code enters a loop and stays there until the pin is high.

What happens is sometimes when i am constantly supplying high and low to the ADC pin, at certain point it gets stuck at high detected and gets stuck there even after i remove the high voltage line.
After around 10-20 seconds it says high not detected. Then if I give the high again, it says high detected after another 10-20 seconds or so.

How can it happen when its going through the same loop which worked for an hour?

[Ttelmah]

What is driving the pin?.
What ensures the signal does not go outside the range Vss to Vdd?.

[PCM programmer]

Newguy,
I don't think he has a series crystal, because here is the ECS part
numbering guide:
http://www.ecsxtal.com/store/pdf/partnumber4.pdf
He said his part number is:

[newguy]

The datasheet he linked to mentioned it was a series crystal. That was as far as I dug.

As Ttelmah has said, he probably has a much different issue masquerading as a clock problem.

[Ttelmah]

I too only looked at the sheet he linked to.
However it going wrong after a time, to me suggests something else is 'afoot'.

Best Wishes

[PCM programmer]