[Tinyos-devel] FW: Friendly plea regarding tinyos-2.x cc2420 stack :)

[Kevin Klues]

Can you send us some sample code where the bug is demonstrated?  I
have working code that switches between the radio and flash relatively
quickly (see the LowPowerSensingApp in tos/tutorials) and haven't run
into any problems.  If I can reprodcue the bug I'll spend some time
looking into it.

Kevin

On 10/18/07, David Moss <dmm at rincon.com> wrote:
> Fyi.
>
>
> -----Original Message-----
> From: Leo Szumel [mailto:leo at sentilla.com]
> Sent: Thursday, October 18, 2007 10:40 AM
> To: David Moss
> Subject: Re: Friendly plea regarding tinyos-2.x cc2420 stack :)
>
> David,
>
> Alas, we are using tag "release_tinyos_2_0_2_2". Interestingly, this bug
> only popped up when we started using the Stm25pFlash component in
> conjunction with the CC2420 (both tested fine independently). I have
> verified to my satisfaction that the arbitration is working, and never are
> both devices selected simultaneously (scoped out the CSN pins). So the
> likely candidate seems to be a bug in the MCU's SPI code, perhaps
> incorrectly switching state between the two grants. If you've got any other
> ideas, I'd love to hear 'em.
>
> BTW, I have looked at the bus during the hang, and the CC2420 is still
> selected (CSN low). By examination of the radio stack, this could only
> happen when the SPI resource is granted. It seems impossible (with my
> knowledge of 2.0.2.2) that a higher layer could release the grant without,
> in this instance, CC2420TrasmitP having first released it.
>
> Thanks for your super fast reply!
>
> -Leo
>
> ----- Original Message -----
> From: "David Moss" <dmm at rincon.com>
> To: "Leo Szumel" <leo at sentilla.com>
> Sent: Thursday, October 18, 2007 10:00:19 AM (GMT-0800) America/Los_Angeles
> Subject: RE: Friendly plea regarding tinyos-2.x cc2420 stack :)
>
> Hi Leo,
>
> Yes, I do know what's going on, and my first guess is you're still using the
> CC2420 from TinyOS 2.0.0 or 2.0.1.  Right?  If so, you should try to upgrade
> your CC2420 stack to the latest and greatest 2.0.2 release.  Btw, what's in
> the CVS baseline right now is 2.1, with interface changes and stuff, so I'd
> recommend trying to get the actual 2.0.2 release so you don't break the rest
> of your code.  You should be able to just copy in the new CC2420 chip from
> 2.0.2 and modify your .platform file to include all of the chip's new
> directories correctly at compile time.
>
> What's happening here is the CC2420 radio is releasing the SPI bus in the
> middle of a SPI bus operation.  This is because the radio duty cycling
> component doesn't know when the SPI bus is in use, it just knows when the
> radio should be turning off.  And the lower levels of the stack didn't
> really care when the SPI bus was in use, so the radio gets turned off, the
> SPI resource is released, and the SPI bus driver hangs.  Something like that
> anyway.  There was some traffic on this bug a few months ago in tinyos-help
> where I explained in detail what was going on.
>
> The current CC2420 stack allows the SPI bus to complete its task before
> releasing it, even if the radio gets physically shut off in the middle of a
> SPI bus operation. Because the microcontroller is the master, the SPI bus
> will complete its task regardless of whether or not the radio is physically
> turned on.  The CC2420 driver itself knows that the SPI driver events are
> returning garbage because the radio's off, and at that point, the SPI
> resource is released and everything's happy.
>
> -David
>
>
>
>
>
>
>
> -----Original Message-----
> From: Leo Szumel [mailto:leo at sentilla.com]
> Sent: Thursday, October 18, 2007 9:39 AM
> To: dmm at rincon.com
> Subject: Friendly plea regarding tinyos-2.x cc2420 stack :)
>
> Hi David,
>
> Remember me from my questions/bug reports regarding the tos-1.x blackbook
> implementation? Good news is I was able to build my app by side stepping the
> various bugs I was experiencing.
>
> Bad news is I have another question for you! But, it's just a "got any
> ideas?" question.
>
> I'm running (more or less) the vanilla tinyos-2.x radio stack and it's
> hanging. We are using TelosB hardware, which means the SPI bus is shared by
> the external Stm25pFlash chip and the CC2420. I send this plea to you
> because I know you have spent a lot of time developing the tos-2.x cc2420
> code and I'm hoping you may have hit this before and have some insight.
>
> Using a debugger I can see that the MCU is stuck in this loop:
>
> Msp430SpiNoDmaP.nc:111
>
>   async command uint8_t SpiByte.write( uint8_t tx ) {
>     uint8_t b;
>     // we are in spi mode which is configured to have turned off interrupts
>     //call Usart.disableRxIntr();
>     call Usart.tx( tx );
> >>>>while( !call Usart.isRxIntrPending() );
>     call Usart.clrRxIntr();
>     b = call Usart.rx();
>     //call Usart.enableRxIntr();
>     return b;
>   }
>
> i.e., stuck polling for the readback byte after sending a spi byte.
>
> What is confusing is that the readback byte should *always* be available
> since that's core to the SPI protocol. The only way I can imagine this
> happening is if the MCU's SPI mode is misconfigured. Currently I'm going to
> do more register examination in the debugger and maybe some logic analyzer
> traces from the bus.
>
> In the meantime, I'm praying you will say "aha! I remember that" and give me
> valuable insight that will save me some time :).
>
> Best,
>
> -Leo
>
>
>
>
>
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-- 
~Kevin