USB/DFU

Overview

AM62Ax USB peripheral boot (also called device boot) mode receives a second bootloader image from a USB host using the Device Firmware Update (DFU) specification defined by USB-DFU.

This section demonstrates how to use DFU to boot phyCORE-AM62Ax to a U-Boot prompt using a Linux Ubuntu PC.

Setup

Hardware

Ubuntu 22.04 LTS, 64-bit Host Machine
- If using a virtual machine, VMWare Workstation, VMWare Player, and VirtualBox are all viable solutions.
USB-C to USB-A cable

Software

Prepare the following U-Boot images for downloading to and booting on the phyCORE-AM62Ax via DFU:
```
* tiboot3.bin-perif
* tispl.bin
* u-boot.img
```
tiboot3.bin-perif is built along side tiboot3.bin and is used for periferal boots on the AM62Ax.

Install & Configure Snagboot

Install python3, pip, and swig:

Host (Ubuntu)

$ sudo apt update && sudo apt install python3 python3-pip python3-venv swig

Now we can create our python virtual environment in the same folder that we have our U-Boot images
Host (Ubuntu)
```
$ python3 -m venv myenv
$ source myenv/bin/activate
```
Install snagboot in our venv using pip
Host (Ubuntu)
```
$ pip install snagboot
```

Export our template

Host (Ubuntu)

$ snagrecover -t am62x-phyboard-lyra > am62x-phyboard-lyra.yaml

We can cat the template to verify it is exported correctly:

Host (Ubuntu)

$ cat am62x-phyboard-lyra.yaml

tiboot3:
  path: tiboot3.bin-perif
tispl:
  path: tispl.bin
u-boot:
  path: u-boot.img

Note

At this point if we run ls our folder should include the following:

$ ls

am62x-phyboard-lyra.yaml
myvenv
tiboot3.bin
tiboot3.bin-perif
tispl.bin
u-boot.img

Booting from USB/DFU

Here are the basic steps for booting from USB/DFU on the phyCORE-AM62Ax development kit. The steps for establishing a serial communication are outlined in the Quickstart.

Note

We should have two terminals open at this point. One for running commands via USB-C and an open Serial connection to see the SoMs boot status.

Plug a USB-C cable from the phyCORE-AM62Ax development kit into your Ubuntu machine.
Adjust boot switch settings on the phyCORE-AM62Ax development kit.
Power on the phyCORE-AM62Ax development kit.

At this point you should see the kit appear on your Ubuntu machine via the USB-C. To verify this, run the following:

Host (Ubuntu USB-C)

$ lsusb | grep 0451:6165

Bus 005 Device 060: ID 0451:6165 Texas Instruments, Inc. AM62x DFU

We can now begin our recovery by running snagrecover on our Ubuntu machine.

Host (Ubuntu USB-C)

$ snagrecover -s am625 -f am62x-phyboard-lyra.yaml --rom-usb 0451:6165

  Starting recovery of am625 board
  Installing firmware tiboot3
  Searching for partition id...
  Downloading file...
  Could not read status after end of manifest phase
  Done
  Done installing firmware tiboot3
  Installing firmware u-boot
  Searching for partition id...
  Downloading file...
  Done
  Done installing firmware u-boot
  Installing firmware tispl
  Searching for partition id...
  Downloading file...
  Done
  Sending detach command...
  Done installing firmware tispl
  Done recovering am625 board

We should see the following response letting us know the tispl has been loaded:

Host (Ubuntu Serial)

NOTICE:  BL31: Built : 09:34:15, Aug 24 2023

U-Boot SPL 2023.04-gcef86e5f6f (Nov 01 2023 - 19:03:02 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0009 '9.0.5--v09.00.05 (Kool Koala)')
SPL initial stack usage: 1856 bytes
Trying to boot from DFU

We can then run the next command to load U-Boot:

Host (Ubuntu USB-C)

$ snagflash -P dfu -p 0451:6165 -D 1:u-boot.img

Downloading u-boot.img to altsetting 1...
progress:100%
Done
Sending DFU detach command...
Done

At this point we should see U-Boot start up and attempt to boot from the SD-Card on our Serial terminal. We can stop in U-Boot by pressing any key at this point.

Boot Switch Settings

S7 should be ON to overide default boot settings.