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Elkhart Lake CRB

Overview

Elkhart Lake Reference Board (EHL CRB) is an example implementation of a compact single board computer with high performance for IoT edge devices.

This board configuration enables kernel support for the EHL board.

Note

This board configuration works on the variant of EHL boards containing Intel® Atom™ SoC.

Hardware

General information about the board can be found at the EHL website.

Supported Features

In addition to the standard architecture devices (HPET, local and I/O APICs, etc.), Zephyr supports the following Elkhart Lake-specific SoC devices:

I2C

UART Serial Port Support

The Elkhart Lake UARTs are NS16550-compatible. Baud rate of 115.2kbps is supported.

Connections and IOs

Refer to the EHL website for more information.

Programming and Debugging

Use the following procedures for booting an image on a EHL CRB board.

Build Zephyr application
Preparing the Boot Device
Booting the Elkhart Lake CRB Board
Booting the Elkhart Lake CRB Board over network

Build Zephyr application 

Build a Zephyr application; for instance, to build the hello_world application on Elkhart Lake CRB:
```
# From the root of the zephyr repository
west build -b ehl_crb samples/hello_world
```
Note

A Zephyr EFI image file named zephyr.efi is automatically created in the build directory after the application is built.

Preparing the Boot Device 

Prepare a USB flash drive to boot the Zephyr application image on an Elkhart Lake CRB board.

Format the USB flash drive as FAT32.

On Windows, open File Explorer, and right-click on the USB flash drive. Select Format.... Make sure in File System, FAT32 is selected. Click on the Format button and wait for it to finish.

On Linux, graphical utilities such as gparted can be used to format the USB flash drive as FAT32. Alternatively, under terminal, find out the corresponding device node for the USB flash drive (for example, /dev/sdd). Execute the following command:
```
$ mkfs.vfat -F 32 <device-node>
```
Important

Make sure the device node is the actual device node for the USB flash drive. Or else you may erase other storage devices on your system, and will render the system unusable afterwards.
Copy the Zephyr EFI image file zephyr/zephyr.efi to the USB drive.

Booting the Elkhart Lake CRB Board 

Boot the Elkhart Lake CRB board to the EFI shell with USB flash drive connected.

Insert the prepared boot device (USB flash drive) into the Elkhart Lake CRB board.
Connect the board to the host system using the serial cable and configure your host system to watch for serial data. See EHL website for more information.

Note

On Windows, PuTTY has an option to set up configuration for serial data. Use a baud rate of 115200.
Power on the Elkhart Lake CRB board.
When the following output appears, press F7:
```
Press <DEL> or <ESC> to enter setup.
```
From the menu that appears, select the menu entry that describes that particular EFI shell.
From the EFI shell select Zephyr EFI image to boot.
```
Shell> fs0:zephyr.efi
```

Booting the Elkhart Lake CRB Board over network 

Build Zephyr image

Follow Build Zephyr application steps to build Zephyr image.

Prepare Linux host

Install DHCP, TFTP servers. For example dnsmasq
```
$ sudo apt-get install dnsmasq
```

Configure DHCP server. Configuration for dnsmasq is below:

# Only listen to this interface
interface=eno2
dhcp-range=10.1.1.20,10.1.1.30,12h

Configure TFTP server.
```
# tftp
enable-tftp
tftp-root=/srv/tftp
dhcp-boot=zephyr.efi
```
zephyr.efi is a Zephyr EFI binary created above.
Copy the Zephyr EFI image zephyr/zephyr.efi to the /srv/tftp folder.
$ cp zephyr/zephyr.efi /srv/tftp/

Restart dnsmasq service:

$ sudo systemctl restart dnsmasq.service

Prepare Elkhart Lake CRB board for network boot

Enable boot from PXE. Go to EFI shell and make sure that the first boot option is UEFI PXEv4.

Shell> bcfg boot dump
Option: 00. Variable: Boot0007
  Desc    - UEFI PXEv4 (MAC:6805CABC1997)
  DevPath - PciRoot(0x0)/Pci(0x1C,0x0)/Pci(0x0,0x0)/MAC(6805CABC1997,0x0)/IPv4(0.0.0.0)
  Optional- Y
...

If UEFI PXEv4 is not the first boot option use bcfg boot mv command to change boot order
```
Shell> bcfg boot mv 7 0
```

Booting Elkhart Lake CRB

Connect the board to the host system using the serial cable and configure your host system to watch for serial data.
Power on the Elkhart Lake CRB board.

Verify that the board got an IP address:

$ journalctl -f -u dnsmasq
dnsmasq-dhcp[5386]: DHCPDISCOVER(eno2) 00:07:32:52:25:88
dnsmasq-dhcp[5386]: DHCPOFFER(eno2) 10.1.1.28 00:07:32:52:25:88
dnsmasq-dhcp[5386]: DHCPREQUEST(eno2) 10.1.1.28 00:07:32:52:25:88
dnsmasq-dhcp[5386]: DHCPACK(eno2) 10.1.1.28 00:07:32:52:25:88

Verify that network booting is started:

$ journalctl -f -u dnsmasq
dnsmasq-tftp[5386]: sent /srv/tftp/zephyr.efi to 10.1.1.28

When the boot process completes, you have finished booting the Zephyr application image.