Parallel_Boot
No
Yes
Initialize GP I/O MUX
and Dir registers
AIO[31,30,5:0] = input
AIO12 = input
AIO6 = output
Valid
KeyValue
(0x08AA)
?
reserved words
Read and discard 8
Read EntryPoint
address
CopyData
Call
Return
EntryPoint
Enable pullups on
GPIO[31,30,5:0]
Jump to Flash
Figure 2-17. Parallel GPIO Mode Overview
shows the transfer flow from the host side. The operating speed of the CPU and host are not critical
in this mode as the host will wait for the 28x and the 28x will in turn wait for the host. In this manner the protocol
will work with both a host running faster and a host running slower than the 28x.
Start transfer
No
More
data
?
28x ready
(AIO6=0)
?
Yes
Load GPIO[31,30,5:0] with data
Signal that data
is ready
(AIO12=0)
28x ack
(AIO6=1)
?
No
Yes
Acknowledge 28x
(AIO12=1)
Yes
No
End transfer
Figure 2-18. Parallel GPIO Mode - Host Transfer Flow
Boot ROM
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
225
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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