SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
When a 32-bit message is written to the MAILBOX_MESSAGE_m register, the message is appended into the FIFO queue. This queue holds four messages. If the queue is full, the message is discarded.
Queue overflow can be avoided by first reading the MAILBOX_FIFOSTATUS_m register to check that the mailbox message queue is not full before writing a new message to it.
Reading the MAILBOX_MESSAGE_m register returns the message at the beginning of the FIFO queue and removes it from the queue. If the FIFO queue is empty when the MAILBOX_MESSAGE_m register is read, the value 0 is returned.
The new message interrupt is asserted when at least one message is in the mailbox message FIFO queue. To determine the number of messages in the mailbox message FIFO queue, read the MAILBOX_MSGSTATUS_m register.