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Table 2-11. Parallel GPIO Boot 8-Bit Data Stream
Bytes
GPIO[ 31,30,5:0]
(Byte 1 of 2)
GPIO[ 31,30,5:0]
(Byte 2 of 2)
Description
1
2
AA
08
0x08AA (KeyValue for memory width = 16 bits)
3
4
00
00
8 reserved words (words 2-9)
...
...
...
...
...
17
18
00
00
Last reserved word
19
20
BB
00
Entry point PC[22:16]
21
22
DD
CC
Entry point PC[15:0] (PC = 0x00BBCCDD)
23
24
NN
MM
Block size of the first block of data to load = 0xMMNN words
25
26
BB
AA
Destination address of first block Address[31:16]
27
28
DD
CC
Destination address of first block Address[15:0] (Address = 0xAABBCCDD)
29
30
BB
AA
First word of the first block in the source being loaded = 0xAABB
...
...
...
Data for this section.
...
.
BB
AA
Last word of the first block of the source being loaded = 0xAABB
.
NN
MM
Block size of the 2nd block to load = 0xMMNN words
.
BB
AA
Destination address of second block Address[31:16]
.
DD
CC
Destination address of second block Address[15:0]
.
BB
AA
First word of the second block in the source being loaded
.
…
n
n+1
BB
AA
Last word of the last block of the source being loaded
(More sections if required)
n+2
n+3
00
00
Block size of 0000h - indicates end of the source program
The 28x device first signals the host that it is ready to begin data transfer by pulling the AIO6 pin low. The host
load then initiates the data transfer by pulling the AIO12 pin low. The complete protocol is shown in the diagram
below:
Host control
AIO12
28x control
AIO6
1
2
3
4
6
5
Figure 2-16. Parallel GPIO Boot Loader Handshake Protocol
1. The 28x device indicates it is ready to start receiving data by pulling the AIO6 pin low.
2. The bootloader waits until the host puts data on GPIO [31,30,5:0]. The host signals to the 28x device that
data is ready by pulling the AIO12 pin low.
3. The 28x device reads the data and signals the host that the read is complete by pulling AIO6 pin high.
4. The bootloader waits until the host acknowledges the 28x by pulling AIO12 pin high.
5. The 28x device again indicates it is ready for more data by pulling the AIO6 pin low.
This process is repeated for each data value to be sent.
shows an overview of the Parallel GPIO bootloader flow.
Boot ROM
224
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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