This version (27 Jan 2021 22:42) was approved by Robin Getz.The Previously approved version (19 Aug 2019 19:49) is available.Diff

USB OTG – HOST function Support

When the device is powered from the Auxiliary Power Supply it support various HOST functions, such as USB WIFI, Storage and HID. Using the correct cables is the key to OTG operation.

USB Wifi Support

PlutoSDR or M2k allows WIFI connectivity using ESSID and WPA-PSK passphrase. The ESSID and Passphrase is set using the config.txt file in the Mass Storage Device. The ESSID string is at most 32 alphanumeric characters, and the passphrase is at least 8 and at most 63 ASCII characters.

Supported WIFI chipsets

Linux supports a large number of USB 802.11 WIFI modules. Most of these also require a firmware file to be available on the host device. Given the constrained flash memory footprint of the device, the decision was made to support only a number of popular Ralink and Realtek based chipset modules. This includes also a few unstable drivers from the kernel staging area, so not all modules will work equally well.

Supported chipsets:

  • Ralink rt2501/rt61
  • Ralink rt73
  • Ralink rt27xx/rt28xx/rt30xx
  • Realtek 81xx
  • Realtek 87xx
  • Realtek 88xx

Many cheap and widely available modules will work - If you need a recommendation. The models listed below have been tested:

  • TP-Link TL-WN725N Nano WLAN
  • Cisco WUSB600N V2

USB Wired Ethernet Support

If you want to integrate the PlutoSDR or M2k into a wired Ethernet network directly, without PC in between. Use a wired USB Ethernet adapter. Even though the USB support on PlutoSDR or M2k is only USB 2.0 HIGH SPEED. It’s still beneficial to purchase a USB 3.0 Gigabit Ethernet Adapter. Using those USB 3.0 Gigabit Ethernet Adapters (in IIOD network back-end mode) the throughput can be on par of with the IIOD USB back-end.

Supported chipsets:

  • ASIX AX88xxx Based USB 2.0 Ethernet Adapters
  • ASIX AX88179/178A USB 3.0/2.0 to Gigabit Ethernet
  • Microchip LAN78XX Based USB Ethernet Adapters
  • Realtek RTL8152/RTL8153 Based USB Ethernet Adapters
  • SMSC LAN75XX based USB 2.0 gigabit ethernet devices
  • SMSC LAN95XX based USB 2.0 10/100 ethernet devices

Many cheap and widely available modules will work - If you need a recommendation. The models listed below have been tested:

Mass Storage Drive Support

PlutoSDR or M2k allows in OTG Host mode the attachment of USB Mass Storage Devices. The supported file system is currently FAT/FAT32 only. Kernel Hotplug mechanisms are used to automount the available partitions under /media. Once the storage is mounted the LED1 will stay constantly ON. Upon storage removal the media is un-mounted and the LED1 will resume its heartbeat flash. There is also a save unmount functionality implemented using the hidden button. If pressed while a media is mounted the media is unmounted and the LED1 will also resume to heartbeat flash.

Someone may ask what’s the purpose of the USB Mass Storage Device Support?

Auto Run Support

After mounting the attached storage the filesystem root is scanned for files named runme[XX][.sh]. Where XX is optional or can be any decimal numbers starting from 0..99. The number defines the sequence in which the scripts or executables are executed. If the file extension is .sh the shell script is sourced for speed. If no .sh extension a subprocess is forked.

university/tools/pluto/usb_otg_host_function_support.txt · Last modified: 27 Jan 2021 22:37 by Robin Getz