8-Bit Parallel Getword Function - Texas Instruments Concerto F28M36 Series Technical Reference Manual

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Signal host that device is ready
Device ack read complete
6.7 Guidelines for Boot ROM Application Writers
This section provides guidelines to write a master subsystem application in order to kick-start a peripheral
bootloader on C-Boot ROM or to let the control subsystem boot to flash.
6.7.1 Master Subsystem Application Procedure to Start C-Boot ROM Bootloaders
As previously explained, M-Boot ROM brings the control subsystem out of reset so that it can execute C-
Boot ROM and M-Boot ROM will continue to execute its own application. Mean-while C-Boot ROM
initializes the control subsystem as explained and puts C28x CPU in IDLE Low Power Mode. It is up to the
master subsystem application to decide on how it wants to let the control subsystem boot and function.
The flow diagrams and procedures listed below in this section explain the minimum things that should be
done in order to successfully boot the control subsystem.
SPRUHE8E – October 2012 – Revised November 2019
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Figure 6-31. 8-Bit Parallel GetWord Function
Parallel_GetWordData
8 bit
(GPIO26 = 0)
Data
No
ready
(GPIO27 = 0)
?
Yes
Read word of data
from GPIO[9,8,5:0]
(GPIO26 = 1)
Host
No
ack
(GPIO27 = 1)
?
Yes
A
Copyright © 2012–2019, Texas Instruments Incorporated
Guidelines for Boot ROM Application Writers
A
Signal host that device
is ready to read MSB
(GPIO26 = 0)
Data
No
ready
(GPIO27 = 0)
?
Yes
Read GPIO [15:0] with
GPIO[9:8] masked into
GPIO[7:6] for LSB of data.
Discard GPIO[15:8].
Repeat for MSB of data.
Device ack read complete
(GPIO26 = 1)
Host
ack No
(GPIO27 = 1)
?
Yes
WordData = MSB:LSB
Return WordData
ROM Code and Peripheral Booting
657