Setting Up the i.MX 8M Mini SOM Starter Kit Print


Unpacking the Kit

The i.MX 8M Mini kit arrives packaged into a plastic box. The following picture illustrates the package you would be receiving from Emcraft:

Please notice the printed label on the top of the box. Please store or photograph the label, it may be needed if you need to contact Emcraft Support with questions or support issues.

Open the box, remove the cables. The following picture illustrates the kit at this stage of unpacking:

Note that the various boards included in the kit are secured to the plastic box using velcro patches. This is done to ensure mechanical security of the kit while in transit. You will need to remove the boards from the plastic box. To do so, carefully unfasten the boards from the velcro patches and separate the boards from the plastic box. The following picture illustrates the kit at the final stage of unpacking:


Understanding Kit Contents

As shipped by Emcraft, the kit is assembled as a miniature 3-layers "Cube". This "Cube", when assembled together, presents an i.MX 8M Mini-based embedded computer, composed of the following stacked hardware modules:

  • i.MX 8M Mini System-On-Module (SOM), which integrates the NXP i.MX 8M Mini Quad SoC, 2GB LPDDR4, 4GB eMMC, WiFi/BT on a miniature (50mm x 50mm) computer module, connected to a carrier board using 3 board-to-board connectors. The i.MX 8M Mini SOM is an Emcraft off-the-shelf System-On-Module product, ready for deployment in various embedded applications.
  • MEDIA board is a second board in the stack, which provides various UI and I/O interfaces. The SOM plugs onto the MEDIA board.
  • HGI (HoverGamesInterposer) board is a third board in the stack, which provides additional connectivity and I/O interfaces. The MEDIA board plugs onto the HGI board.

The following add-on boards are included in the kit:

  • USB-to-UART converter "dongle";
  • MIPI-DSI2-to-HDMI converter "dongle".

The following cables are included in the kit:

  • USB Type C to USB Type A cable;
  • Ethernet cable;
  • HDMI cable.

Setting Up Serial Console

The serial console UART interface is used to get access to the i.MX 8M Mini U-Boot and Linux serial console. This is the primary user interface the kit provides to software developers. You won't be able to do much unless you have access to the serial console.

Both U-Boot and Linux are configured to use the i.MX 8M Mini UART2 port for the serial console. The kit provides UART2 as a 3.3V interface on the 6-pin "U2" connector residing on the HGI board. In order to connect the serial console to a PC, you must convert the 3.3V UART interface to a USB serial interface. This requires connecting an external device ("USB-to-UART converter dongle") to the kit. The kit comes cabled to such a dongle, so all you have to do to plug the USB end of the dongle to your PC. Just in case, the following table provides pin-out of the "U2" port on the HGI board:

UART2 Connector Pin# Signal Name Description
1 5VP +5V
2 UART2_TXD UART TX
3 UART2_RXD UART RX
4 SAI3_RXC UART CTS
5 SAI3_RXD UART RTS
6 GND Ground


To complete connection of the serial console to your PC, plug the USB end of the USB--UART dongle into a free USB port on your PC. The LED On the USB-to-UART dongle should lit up at this point:


Linux running on the PC will recognize the new serial device and make it available in the system as a /dev/ttyUSBx TTY device. Use the dmesg utility to determine a specific TTY device Linux has assigned to the serial console port on your kit:

$ dmesg | tail
[495846.154337] cp210x 1-5.1.5:1.0: cp210x converter detected
[495846.216898] usb 1-5.1.5: reset full-speed USB device number 8 using ehci-pci
[495846.292179] usb 1-5.1.5: cp210x converter now attached to ttyUSB0

On the kit side, U-Boot and Linux configure the serial console as follows: 115200 bps, N, 8, 1 (8 bit, no parity, no flow control). Use your favorite Linux serial terminal utility to connect to the kit serial console from the Linux host. For instance:

$ picocom –l /dev/ttyUSB0 –b 115200


Powering Up

To power the kit up, plug the USB Type C to USB Type A cable between the USB Type C port on the HGI board and a free USB port on your PC host. The kit will power up as soon as power is applied via the USB cable:

Note: Power consumption of the kit, comprised of the 3 stacked hardware modules with the add-on boards and depending on software configuration, may exceed 7-8W or be even higher in some I/O intensive configurations. We recommend connecting the kit to the following USB power supplies:

Running First Linux Session

The i.MX 8M Mini SOM arrives with default Linux images pre-installed to eMMC storage. As soon as the kit is powered up, Linux will boot up, with the following messages showing up in your serial terminal window:

U-Boot SPL 2019.04+gd62847f248 (May 19 2020 - 09:22:02 +0000) power_bd71837_init DDRINFO: start DRAM init DDRINFO:ddrphy calibration done DDRINFO: ddrmix config done Normal Boot Trying to boot from MMC2 U-Boot 2019.04+gd62847f248 (May 19 2020 - 09:22:02 +0000) CPU: Freescale i.MX8MMQ rev1.0 1800 MHz (running at 1200 MHz) CPU: Commercial temperature grade (0C to 95C) at 36C Reset cause: POR Model: Emcraft i.MX8MM Cube board DRAM: 2 GiB ... Starting kernel ... [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034] [ 0.000000] Linux version 5.4.3+ga922dd67988c (oe-user@oe-host) (gcc version 9.2.0 (GCC)) #1 SMP PREEMPT Tue May 19 10:16:49 UTC 2020 ... i.MX 8M Mini Release beta1-20200519 imx8mmcube ttymxc1 imx8mmcube login:

Enter the root account, with an empty password. At this point, you are running the Linux shell on the i.MX 8M Mini and have access to all Linux controls and capabilities as the superuser.


Using Other I/O Interfaces

Use of the advanced I/O interfaces provided by the kit, such as 1GB Ethernet, MIPI-DSI, MIPI-CSI, HMDI and others, is discussed in the follow-up application notes available on the Emcraft web site.


Troubleshooting

In case you are unable to get a Linux session on your kit, step through the following troubleshooting steps, in the descending order:

  • Obtain power through a link to a USB port in a PC or notebook. Using a smartphone power supply or an unpowered USB hub may result in insufficient power to the kit.
  • Configure the serial terminal program for the exact UART parameters specified above in this note. Make sure you disable flow control (modem control) in the terminal program.
  • On some Linux distributions, connecting to a UART/USB device causes the Modem Manager package to try opening the TTY device and sending modem commands to it, thus occupying the port. To avoid this effect, the ModemManager package must be disabled on the host with the following command:
  • sudo mv /usr/share/dbus-1/system-services/org.freedesktop.ModemManager.service /usr/share/dbus-1/system-services/org.freedesktop.ModemManager.service.disabled

  • Double-check that the boot device switches set up for boot from eMMC, as documented in Installing Linux Using USB Serial Downloader.
  • Re-install Linux image to the i.MX 8M Mini via the USB Serial Downloader, as documented in Installing Linux Using USB Serial Downloader.
  • If the above steps do not help, contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it with a detailed description of your problem. We will do our best to help quickly.