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Copyright 2008 Cirrus Logic, Inc.
DS732UM7
Softboot
CS4953xx Hardware Users Manual
2.4.2 Softboot Procedure
Below is a flow diagram and description of the Softboot procedure. This is a step-by-step guideline that can be used
as an aid in developing the system controller code required to drive the CS4953xx.
Figure 2-5. Soft Boot Sequence Flowchart
2.4.2.1 Softboot Procedure
1.
Send the SOFTBOOT message. The host sends the SOFTBOOT message to the CS4953xx to begin overlay
swap.
2.
Wait for IRQ low. The host then waits for SCP1_IRQ (or PCP_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 CS4953xx (for
example, SLAVE_BOOT, HCMB_<MODE>), 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 CS4953xx overlays. If no overlay, change as
required, and go to Step 10,
.
MSG == SOFTBOOT_ACK?
WRITE_* (SOFTBOOT)
READ_* (MSG)
EXIT(ERROR)
N
Y
DONE
LOAD OVERLAYS
START
IRQ == LOW?
N
Y
Y
N
TIMEOUT?
GO TO STEP 10,
Содержание CS4953xx
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