Texas Instruments TMS320 User Manual page 228

Message Queues
6-26
Additionally, MSGQ allows user specified notification mechanisms
(instead of always a semaphore in MBX). So the notification could be the
posting of a SWI. QUE has no type of notification mechanism. It is up to
the application to handle this-for example, by polling or by using
semaphores in the application.
❏ Message Size and Number. The MBX module has a fixed length and
number of messages per mailbox. These values are specified when the
mailbox is created. Both QUE and MSGQ allow for variable sized
messages. They have no maximum number of messages that may be
waiting to be received.
❏ Complexity and Footprint. The MSGQ module offers many advanced
features. However, this comes with added complexity and a larger
footprint. For applications that do not need these advanced features and
flexibility, the QUE or MBX modules might be a better solution because
of lower footprint and easier use.