Other Parts Discussed in Thread: AM3703
Hello,
I am designing a board with the AM3703. It is my first attempt with a TI ARM processor, so perhaps these are obvious questions (I hope so!).
I would prefer to have the boot process be setup as follows:
- Boot from UART3 into Flash hanging off the GPMC bus
- Reset and boot from Flash into DDR
- Finally execute the image out of DDR
In the AM/DM37xx TRM (sprugn4k.pdf), booting from a peripheral is described in 26.4.5.1. Here are some excerpts that apply:
- "The purpose of booting from a peripheral is to boot from an external host, such as a PC. This booting method is used primarily for programming flash memories connected to the device." (my emphasis)
- "The image is downloaded directly at address 0x40200000 in the internal RAM. The ROM code waits up to 1 minute for completion. If the downloading procedure does not complete before this period, the peripheral booting fails. If the download passes, the peripheral booting succeeds and the image can be executed."
The first excerpt implies that the image can go from UART3 into Flash. However, the second excerpt implies that the image is loaded into internal RAM (clearly not large enough to hold the entire image, therefore it must transfer the image elsewhere) and when complete, executes. I did not see any further description or message header/configuration that would specify the destination of the UART3-transmitted message as being Flash, although it's entirely possible I missed it. Also, the many good flow charts don't seem to address it either. So here are my questions.
- Can the image be transferred by Boot ROM code from UART3 into Flash on the GPMC bus?
- If not, how can the information be transferred from RAM into Flash following the boot?
- If yes, how does the Boot code know to where to put the image?
- If what I want to do is not possible, what is the best alternate approach for booting a new image into Flash?
Thanks in advance for whatever help anyone can provide.
Regards,
Bob
