Using the Mailbox - 4.0 English

The mailbox start location within the register map (REG_MAP) is defined by register HOST_MSG_OFFSET_REG.

The following details the mailbox operation.

1. The host checks the availability of the mailbox by confirming CONTROL_REG[5] is 0.
2. The host writes a request message to the mailbox.
3. The host sets CONTROL_REG[5] to 1 to indicate a new request message is available to CMS firmware.
4. The host polls CONTROL_REG[5] until CMS firmware sets to 0, indicating the CMS response message is in the mailbox.
5. The host reads HOST_MSG_ERROR_REG to confirm no message errors are present.
6. If no errors are reported, the host reads the response message from the mailbox.

Figure 1. Mailbox Layout