SCIA_GetWordData
Yes
NoData
Received
?
Echoback LSB
to host
Read LSB
Data
Received
?
No
Yes
Read MSB
Echoback MSB
to host
Return MSB:LSB
2.16 Parallel_Boot Function (GPIO)
DSP
DSP control − GPIO26
Host control − GPIO27
Host
(Data and program
source)
Data GP I/O port GPIO[15:0]
16
Parallel_Boot Function (GPIO)
Figure 2-12. Overview of SCI_GetWordData Function
The parallel general purpose I/O (GPIO) boot mode asynchronously transfers code from GPIO0-GPIO15
to internal memory. Each value can be 16 bits or 8 bits long and follows the same data flow as outlined
inData Stream Structure.
Figure 2-13. Overview of Parallel GPIO bootloader Operation
The 28x communicates with the external host device by polling/driving the GPIO27 and GPIO26 lines. The
handshake protocol shown in Figure 2-14 must be used to successfully transfer each word via
GPIO[15:0]. This protocol is very robust and allows for a slower or faster host to communicate with the
DSP.
If the 8-bit mode is selected, two consecutive 8-bit words are read to form a single 16-bit word. The most
significant byte (MSB) is read first followed by the least significant byte (LSB). In this case, data is read
from the lower eight lines of GPIO[7:0] ignoring the higher byte.
The DSP first signals the host that the DSP is ready to begin data transfer by pulling the GPIO26 pin low.
The host load then initiates the data transfer by pulling the GPIO27 pin low. The complete protocol is
shown in the diagram below:
SPRU722C – November 2004 – Revised October 2006 Bootloader Features 35
Submit Documentation Feedback
To Next Page
Loading...
Need help?
General
