On Sep 19, 2006, at 3:17 PM, David Moss wrote:
Are you accessing the Flash memory while using the radio? I
believe I ran
into some serious issues doing this with the MicaZ. The problem, I
believe,
is in the bus arbitration - because both the flash and the radio
use the
same SPI bus lines, if you're actively using flash and radio
together on a
micaz, the mote crashes.
That's interesting; I believe that the flash and CC2420 do not share
an SPI bus on the mica platforms.
This doesn't happen with telos motes.
I am about to start testing TinyOS 2.x to see if it still has this
problem.
I believe it shouldn't and doesn't because it has a better bus
resource
arbitration story. i.e. the radio has to request access to the bus
before
using it, and the flash has to request access before using it, etc.
Yes, this has been a major focus for 2.x. The bus on the Telos
platform is heavily overloaded (SPI to radio, SPI to flash, I2C for
sensors, UART, etc.) and so requires a lot of effort to abstract
properly in a way that's flexible and robust.
It turns out that this actually simplifies code in a lot of other
ways, though. For example, the radio stack actually has the receive
and transmit paths be separate users of the bus, which individually
arbitrate for it.
Phil
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