Instant Interrupts - Revisited

[Demon]

Steve, I don't know how to check how often the USBSERVICE interrupt is occurring. The only settings I have are the oscillator and prescaler:

DEFINE OSC 48
T1CON = $11 ; Prescaler = 2, TMR1ON

I am using a 20MHz crystal with these configuration settings:

CONFIG PLLDIV = 5 ;Divide by 5 (20MHz input)
CONFIG CPUDIV = OSC1_PLL2 ;[OSC1/OSC2 Src: /1][96MHz PLL Src: /2]
CONFIG USBDIV = 2 ;Clock source from 96MHz PLL/2
CONFIG FOSC = HSPLL_HS ;HS oscillator, PLL enabled, HS used by USB

Robert


EDIT: Interesting, I added a counter in the interrupt routine and displayed it on the LCD, it only gets executed once. I'm checking now if I disable it and never re-enable it after.

[mister_e]

your pre-scaller is way too low... so interupt ocure way too fast, USBSERVICE don't have time to finish correctly.

[Demon]

Do you have a suggestion?

Robert

[mister_e]

Uh... my calculation were wrong... (1/12000000)*65536*2='round 10mSec. ARRGGH i don't have my stuff here to compare with mine... Darrel is on-line anyway

[mister_e]

NO.. let's look at that...

T1CON = $11 ; Prescaler = 2, TMR1ON

i remind that TiCON can be use in 16 bit or 8 bit.. i'm sure you use it in 8 bit mode now... or i missing something obvious about the 16/8 bit.. maybe just in read/write something... mmm something look weird in this line...clock source, mode or else.

[Darrel Taylor]

Well yeah, I'm online. But that's not going to help much since I don't have a Clue about using the USB stuff. Just never got around to trying it before.

I'm still hoping you guys can figure it out. So that when I do get around to trying it, I won't have to work as hard.
<br>
DT

[mister_e]

if i can finish the house-bench-lab-cleaning stuff soon, i'll have access to my stuff. I have this one working.. but i don't remind wich timer i used and how i used it... the T1CON line seems weird... clock source is still my most possible guess.

[Demon]

Uh... my calculation were wrong... (1/12000000)*65536*2='round 10mSec. ARRGGH i don't have my stuff here to compare with mine... Darrel is on-line anyway

Steve, I'm trying to figure this out using math (gotta start sometime) and I'd like to know where you got the 12000000 from.

I read this link you posted in another thread:
http://ww1.microchip.com/downloads/e...Doc/41214a.pdf

And I got this formula from Tip #7:
Tosc x 4 x 65536 x prescaler

I am using a 48MHz crystal so I get this:
(1/48000000) x 4 x 65536 x 2 = 0.0109226 (repeating)

D'uh, ok, I see it now, 48 / 4 = 12, that's where you got your value. So, as you said, that interval rounds up to just over 10ms, that 'should' work.

I'm sure it has something to do with the interrupt occurring right in the middle of USB processing and interfering with the connection. I don't see what else it can be; the interrupt seems fine, the USB works.

Robert