Instant Interrupts - Revisited

**Darrel Taylor** · - 29th December 2006, 05:15

To: Demon and mister_e,

Hey, did you guys ever figure out the USB with DT_INTs approach.

I was thinking about trying a USB project, and wondered if you 2 ever got it working?

**mister_e** · - 30th December 2006, 13:13

Originally Posted by Darrel Taylor

To: Demon and mister_e,

Hey, did you guys ever figure out the USB with DT_INTs approach.

I was thinking about trying a USB project, and wondered if you 2 ever got it working?

Well, i hate to say that Darrel but something goes bad when using instant interrupt and USB. Maybe some PBP variable need to be saved or something like that.

Bellow is a short and sweet working example using ON INTERRUPT to do the USBSERVICE each 100uSec.

OK it doesn't do anything else than sitting there and spin but, it keeps the connection alive without any Windows Warning. Once this solve, it should fix USBOUT and USBIN... or help to

It use a PIC18F4550 and a 4MHZ crystal OSC.

Code:

asm
    __CONFIG    _CONFIG1L, _PLLDIV_1_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L  
                            ;              ;                      ; USB clock source comes from the 96 MHz PLL divided by 2
                            ;              ; [OSC1/OSC2 Src: /1][96 MHz PLL Src: /2]
                            ; No prescale (4 MHz oscillator input drives PLL directly)


    __CONFIG    _CONFIG1H, _FOSC_XTPLL_XT_1H & _FCMEN_OFF_1H & _IESO_OFF_1H 
                            ;                  ;               ; Oscillator Switchover mode disabled
                            ;                  ; Fail-Safe Clock Monitor disabled
                            ; XT oscillator, PLL enabled, XT used by USB
    __CONFIG    _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L  & _BORV_2_2L  & _VREGEN_ON_2L   
    __CONFIG    _CONFIG2H, _WDT_OFF_2H 
    __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H & _CCP2MX_ON_3H 
    __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _ICPRT_OFF_4L  & _XINST_OFF_4L & _DEBUG_OFF_4L 
endasm
DEFINE OSC 48          

PORTB   =   0
TRISB.0 =   0

LED0    VAR PORTB.0
TMR0IF  VAR INTCON.2
TMR0ON  VAR T0CON.7

INTCON  =   %10100000       ' Enable global and TMR0 interrupts
T0CON   =   %10000000       ' TMR0, CLK internal, prescaler 1:2, T0ON

UCFG    var byte EXT        ' include UCFG register... Yeah Melabs didn't :o(

Reload      con 65000       ' ~100 uSec
ucfg    =   %00010100       ' enable internal USB pull-up, Full speed USB

goto SkipMacro
    asm 
Reload_TMR0 macro
    BCF     _TMR0ON         ; stop timer
    MOVE?CW _Reload,TMR0L   ; reload
    BCF     _TMR0IF         ; clear overflow flag
    BSF     _TMR0ON         ; start timer
    ENDM
    endasm

SkipMacro:
    pause 500               ' Settle delay
    usbinit                 ' initialise USB...
@   Reload_TMR0             ; Reload timer0
    ON INTERRUPT GOTO DoUSBService

Start: 
    goto start              ' Spin 'till you die!

DISABLE
DoUSBService:
    toggle LED0             ' toggle LED each time 
    usbservice              ' keep connection alive
@   Reload_TMR0             ; reload timer
    RESUME                  ' getout of here
ENABLE

So nothing complicated... just spinning and keep USB connection alive.

NOW, if i use the DT interrupt, IT SHOULD looks like this

Code:

asm
    __CONFIG    _CONFIG1L, _PLLDIV_1_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L  
                            ;              ;                      ; USB clock source comes from the 96 MHz PLL divided by 2
                            ;              ; [OSC1/OSC2 Src: /1][96 MHz PLL Src: /2]
                            ; No prescale (4 MHz oscillator input drives PLL directly)


    __CONFIG    _CONFIG1H, _FOSC_XTPLL_XT_1H & _FCMEN_OFF_1H & _IESO_OFF_1H 
                            ;                  ;               ; Oscillator Switchover mode disabled
                            ;                  ; Fail-Safe Clock Monitor disabled
                            ; XT oscillator, PLL enabled, XT used by USB
    __CONFIG    _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L  & _BORV_2_2L  & _VREGEN_ON_2L   
    __CONFIG    _CONFIG2H, _WDT_OFF_2H 
    __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H & _CCP2MX_ON_3H 
    __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _ICPRT_OFF_4L  & _XINST_OFF_4L & _DEBUG_OFF_4L 
endasm
DEFINE OSC 48          
PORTB   =   0
TRISB.0 =   0

LED0    VAR PORTB.0
TMR0IF  VAR INTCON.2
TMR0ON  VAR T0CON.7

INTCON  =   %10100000       ' Enable global and TMR0 interrupts
T0CON   =   %10000000       ' TMR0, CLK internal, prescaler 1:2, T0ON

UCFG    var byte EXT        ' include UCFG register... Yeah Melabs didn't :o(

Reload      con 65000       ' ~100 uSec
ucfg    =   %00010100       ' enable internal USB pull-up, Full speed USB

INCLUDE "DT_INTS-18.bas"    ' Base Interrupt System
INCLUDE "ReEnterPBP-18.bas" ' Include if using PBP interrupts

goto skipmacro

    ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler    TMR0_INT,  _DoUSBService,   PBP,  no
    endm
    INT_CREATE               ; Creates the interrupt processor

Reload_TMR0 macro
    BCF     _TMR0ON         ; stop timer
    MOVE?CW _Reload,TMR0L   ; reload
    BCF     _TMR0IF         ; clear overflow flag
    BSF     _TMR0ON         ; start timer
    ENDM
    endasm

SkipMacro:
    pause 500
    usbinit ' initialise USB...
@   Reload_TMR0
@   INT_ENABLE  TMR0_INT

Start: 
    goto start        

DoUSBService:
    toggle led0
    usbservice
@   Reload_TMR0
@   INT_RETURN

Right or i screw something? Anyways ON both, the LED work as expected (so i shouldn't be too wrong) but, the second lost the USB connection really soon... and yeah you have to reboot or it will reboot for you if you disconnect
the USB plug. It's getting boring

i attach everything i have in my C:\PBP_PROG\USBDemo folder, including a compiled VB utility to monitor if the device is Connected or Not when using EasyHID default VendorID and ProductID

So for now, i still use the On Interrupt... Before i read and understand the whole Jan Axelson book, and build my own USB macros, i may need much spare time... oh yeah it's more than a RS-232 and there's a lot of improvements and adds to do with PBP.

Now the weird stuff... Melabs didn't include the 'interesting' registers like UCFG, UIR,UIE,UEIR,UEIE and probably others... bah xxx VAR BYTE EXT fix it for now and if needed.

To be honest, i didn't search really hard to find the problem source... getting lazy i guess :-)

**Darrel Taylor** · - 31st December 2006, 12:18

Wow, it seems like that should work?

That sure gives me a starting point, (good one)

And since you're also in such a good "moon"

I'll take a look at ...
http://www.picbasic.co.uk/forum/showthread.php?t=5418
Too

**mister_e** · - 31st December 2006, 12:26

Well maybe i should say MOOD?
Your Canadian to English dictionnary is still good

Enjoy!

**Darrel Taylor** · - 31st December 2006, 12:39

Well, if I look at my girlfriend ... Moon's and Mood's have the same period, 27.3 days.

Don't know how that fit's in with you though

**mister_e** · - 31st December 2006, 12:45

Yeah, it remind me something... sometimes i'm glad to be 'single'

**Darrel Taylor** · - 7th January 2007, 05:17

Steve,

I got my parts in for USB (gotta love ebay), and I've built up a breadboard with a 4550 and LED's, switches etc.
I've looked at the example from post #143, the second one, with DT_INTS, and found two problems. The ...

INTCON = %10100000 ' Enable global and TMR0 interrupts

was causing the TMR0 interrupts to start servicing the USB before it was initialized. DT_INTS handles all the interrupt enable bits, so you don't need it anyway.

The other problem was ...

goto skipmacro

was skipping over the interrupt defintion. That section of code needs to execute so that it can handle the enable bits and setup a couple other variables.

Once I made those changes, the program works as expected, and never looses connection.
<hr>
But here's the good part,

After going through the USB18.ASM file and seeing how things worked, it soon became apparent that those routines are setup to use the USB interrupts(even though PBP doesn't use them that way). It just needs a "kick-start" to get it going. The "kick-start" is simply a tight loop servicing the USB until the driver gets to the "CONFIGURED_STATE". After that it takes off and handles itself.

But the best part is that it doesn't use ANY PBP system variables to service the USB. So the whole thing can be treated like ASM interrupts, and tied directly into the USB_INT interrupt.

This also seems to improve the response time since it can react immediately to each step of the USB protocol, instead of after each interval of the timer, or whenever ON INTERRUPT get's around to it, but I don't have any hard data to back that up yet.

Here's your PIC program from the [USBDemo, something to learn USB a little bit ]thread /.zip file.
Modified to use DT_INTS-18 and the USB interrupt.
All the other files are the same.

http://www.darreltaylor.com/files/USBDemo2_DT.txt

Works great with the "Mister E USBDemo" program.

Thread: Instant Interrupts - Revisited

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That should do it.

Moon or mood.... that's the question

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