Writing the USRP File System Disk Image to a SD Card

From Ettus Knowledge Base
Jump to: navigation, search

Application Note Number


Revision History

Date Author Details
2018-12-12 Nate Temple Initial creation


This application note will provide step-by-step instructions on writing a file system disk image to a SD card using Linux.

Required Tools

  • Computer with USB2/3 Interface
  • UHD Installation
  • microSD card to USB Adapter

Downloading the File System Image

To obtain the file system SD card image for your USRP device, run the command in the next step on the host computer with UHD installed and Internet access.


   $ sudo uhd_images_downloader -t sdimg -t n3xx

Example Output:

   $ sudo uhd_images_downloader -t sdimg -t n3xx
   [INFO] Images destination: /usr/local/share/uhd/images
   [INFO] No inventory file found at /usr/local/share/uhd/images/inventory.json. Creating an empty one.
   845962 kB / 845962 kB (100%) n3xx_common_sdimg_default-v3.11.1.0.zip
   [INFO] Images download complete.


   $ sudo uhd_images_downloader -t sdimg -t e320

Example Output:

   $ sudo uhd_images_downloader -t sdimg -t e320
   [INFO] Images destination: /usr/local/share/uhd/images
   [INFO] No inventory file found at /usr/local/share/uhd/images/inventory.json. Creating an empty one.
   795674 kB / 795674 kB (100%) e3xx_e320_sdimg_default-v3.13.1.0.zip
   [INFO] Images download complete.

Identifying UHD Installation Prefix

In the output of the uhd_images_downloader command above, the folder destination where the images are saved is printed out.

An alternative method to identify your installation prefix is to run the command:

   $ uhd_config_info --install-prefix

Example Output:

   Install prefix: /usr/local

The default folder location for FPGA and SD card images is:


Writing the File System Image with Linux

Identifying SD Card Mount Location

Insert the microSD card into the host computer.

To identify the device where the microSD card is, run the command:

   dmesg | tail

Example Output (partially truncated for readability):

   [21265.575488] usb-storage 1-2:1.0: USB Mass Storage device detected
   [21266.586983] scsi 0:0:0:0: Direct-Access     Generic  Mass-Storage     1.11 PQ: 0 ANSI: 2
   [21266.588024] sd 0:0:0:0: Attached scsi generic sg0 type 0
   [21267.299812] sd 0:0:0:0: [sdb] 31116288 512-byte logical blocks: (15.9 Gb/14.8 GiB)
   [21267.302687]  sdb: sdb1 sdb2 sdb3 sdb4

NOTE: In this specific example configuration, the SD card has been attached to sdb.

Another method to finding the device node the disk is attached at is to use the Linux utility lsblk:

Example Output:

   $ lsblk
   sdb      8:16   1 14.9G  0 disk
   ├─sdb1   8:17   1   16M  0 part /media/user/boot
   ├─sdb2   8:18   1  1.9G  0 part /media/user/primary
   ├─sdb3   8:19   1  1.9G  0 part /media/user/secondary
   └─sdb4   8:20   1   11G  0 part /media/user/data

Unmount Auto-mounted Partitions

Some operating systems by default will auto-mount the partitions on a block device when it is attached. Before writing a new disk image to the SD card, you should first unmount any mounted partitions. This can be done with the Linux utility umount as shown below:

   $ sudo umount /media/user/data
   $ sudo umount /media/user/primary
   $ sudo umount /media/user/secondary
   $ sudo umount /media/user/boot

Running the command lsblk again will show these partitions have been unmounted:

Example Output:

   $ lsblk
   sdb      8:16   1 14.9G  0 disk
   ├─sdb1   8:17   1   16M  0 part
   ├─sdb2   8:18   1  1.9G  0 part
   ├─sdb3   8:19   1  1.9G  0 part
   └─sdb4   8:20   1   11G  0 part

Writing the SD Card Image

Using dd to write the disk image

WARNING: The Linux utility dd can cause unrecoverable data loss if the incorrect disk is selected, or if the parameters are input incorrectly. Ensure you have selected the correct input and output parameters for your system configuration.

NOTE: You must use a 16 Gb or larger SD card for the N3xx and E320 file system images.

The ​<SD_CARD_DEV_NAME>​ device node depends on your operating system and which other devices are plugged in. Typical values are ​sdb​ or mmcblk0​.

The <IMAGE> value will depend upon which file system image you're writing. Examples for the N300/N310 and E320 are listed below:





Write the disk image with the command:

   $ sudo dd if=<IMAGE> of=<SD_CARD_DEV_NAME> bs=1M

This step of writing the disk image to the SD card can take several minutes to complete.

Example Output:

   $ sudo dd if=/usr/local/share/uhd/images/usrp_<deivce>_fs.sdimg of=/dev/sdb bs=1M
   15160+0 records in
   15160+0 records out
   15896412160 bytes (16 Gb, 15 GiB) copied, 1160.93 s, 13.7 MB/s

To ensure the disk is synchronized, run the sync command:

   $ sync

You can now remove the microSD card from your host computer and insert it into the USRP.

Using bmaptool to write the disk image

The Linux utility bmaptool can be used in place of the utility dd, and will generally write the SD card image faster, however it is not a standard Linux utility and must be installed on your host system.

   $ sudo bmaptool copy <IMAGE> <SD_CARD_DEV_NAME> --bmap <IMAGE BMAP (*.sdimg.bmap)>
   $ sudo bmaptool copy /usr/local/share/uhd/images/usrp_<deivce>_fs.sdimg /dev/sdb --bmap /usr/local/share/uhd/images/usrp_<device>_fs.sdimg.bmap
   bmaptool: info: block map format version 2.0
   bmaptool: info: 3875840 blocks of size 4096 (14.8 GiB), mapped 596649 blocks (2.3 GiB or 15.4%)
   bmaptool: info: copying image ‘/usr/local/share/uhd/images/usrp_<device>_fs.sdimg' to block device '/dev/sdb' using bmap file '/usr/local/share/uhd/images/usrp_<device>_fs.sdimg.bmap'
   bmaptool: info: 100% copied
   bmaptool: info: synchronizing '/dev/sdb'
   bmaptool: info: copying time: 4m 10.3s, copying speed 9.3 MiB/sec