Softboot Steps; Softboot Example; Figure 2-4. Soft Boot Sequence Flowchart - Cirrus Logic CS485 Series User Manual

Softboot
CS485xxr Hardware User's Manual

2.5.2.1 Softboot Steps

1. Send the SOFTBOOT message. The host sends the SOFTBOOT message to the
overlay swap.
2. Wait for IRQ low. The host then waits for SCP_IRQ to go low. If the TIMEOUT period has been
reached, the host should exit. If the IRQ pin is LOW, proceed to step 3.
3. Read the SOFTBOOT_ACK message. If the message is the SOFTBOOT_ACK message
(0x00000005), then the host should proceed to step 4. If the message is not the SOFTBOOT_ACK
message, the host should return to step 2.
4. Load Overlays. Repeat the boot procedure used to originally load the overlays into the
SLAVE_BOOT), but only the overlays that need to be swapped should be loaded. Skip the hard reset
sequence, starting the boot procedure from Step 2. Please note that this includes re-downloading all
hardware and software configurations for the

2.5.2.2 Softboot Example

Figure 2-5 is an example flow diagram and step-by-step description of the Softboot procedure based on the
SLAVE_BOOT procedure described earlier.
2-9
START
WRITE_* (SOFTBOOT)
IRQ == LOW?
Y
READ_* (MSG)
N
MSG == SOFTBOOT_ACK?
Y
LOAD OVERLAYS
DONE

Figure 2-4. Soft Boot Sequence Flowchart

Copyright 2009 Cirrus Logic, Inc.
N
N
TIMEOUT?
Y
EXIT(ERROR)
overlays.
CS485xx
to begin
CS485xx
(i.e.
CS485xx
DS734UM7