Hello,
I need to know the maximal length of a message sent. The SmartPointer class says one payload can maximal be 252byte. Is this the maximal Message size?
Best Regards,
Thorsten
Hello Thorsten,
I need to know the maximal length of a message sent. The SmartPointer class says one payload can maximal be 252byte. Is this the maximal Message size?
Depends on the backend you are using. The standard CAN backend is limited to 8 CAN messages per xpcc message. This results in a maximal length of 6*8 = 48 byte. This can be extended with a different backend, but that is up to you. The next limited is the mentioned smart pointer. The limited there can be increased for >= 8 bit processors or through the use of platform specific synchronization mechanisms. At the moment it avoids explicit atomic operations by operating on a variable size (=8 bit) which can be read atomically by all microprocessors.
Fabian
Hi,
as far as I can see it it makes no sense to use messages, which are bigger than 48byte then, because we try to send the same messages on all platforms.
Thanks for the fast answer,
Best Regards, Thorsten
On 20.09.2013 16:39, Fabian Greif wrote:
Hello Thorsten,
I need to know the maximal length of a message sent. The SmartPointer class says one payload can maximal be 252byte. Is this the maximal Message size?
Depends on the backend you are using. The standard CAN backend is limited to 8 CAN messages per xpcc message. This results in a maximal length of 6*8 = 48 byte. This can be extended with a different backend, but that is up to you. The next limited is the mentioned smart pointer. The limited there can be increased for >= 8 bit processors or through the use of platform specific synchronization mechanisms. At the moment it avoids explicit atomic operations by operating on a variable size (=8 bit) which can be read atomically by all microprocessors.
Fabian
xpcc-dev mailing list xpcc-dev@lists.rwth-aachen.de http://mailman.rwth-aachen.de/mailman/listinfo/xpcc-dev
Hi,
as far as I can see it it makes no sense to use messages, which are bigger than 48byte then, because we try to send the same messages on all
platforms.
I wouldn't impose an arbitrary length limit for other backends (if this is about the TCP/IP backend). I am sure the TIPC Backend doesn't have the 48 byte limit, that was just a design decision to keep the memory footprint of the message management low for AVR microcontroller when using the CAN backend.
Fabian
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Fabian Greif -
Thorsten Lajewski