SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
When a 32-bit message is written to the MAILBOX_MESSAGE_y 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_FIFO_STATUS_y register to check that the mailbox message queue is not full before writing a new message to it.
Reading the MAILBOX_MESSAGE_y 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_y 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_MSG_STATUS_y register.