linux/Documentation/usb/misc_usbsevseg.rst
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   1=============================
   2USB 7-Segment Numeric Display
   3=============================
   4
   5Manufactured by Delcom Engineering
   6
   7Device Information
   8------------------
   9USB VENDOR_ID   0x0fc5
  10USB PRODUCT_ID  0x1227
  11Both the 6 character and 8 character displays have PRODUCT_ID,
  12and according to Delcom Engineering no queryable information
  13can be obtained from the device to tell them apart.
  14
  15Device Modes
  16------------
  17By default, the driver assumes the display is only 6 characters
  18The mode for 6 characters is:
  19
  20        MSB 0x06; LSB 0x3f
  21
  22For the 8 character display:
  23
  24        MSB 0x08; LSB 0xff
  25
  26The device can accept "text" either in raw, hex, or ascii textmode.
  27raw controls each segment manually,
  28hex expects a value between 0-15 per character,
  29ascii expects a value between '0'-'9' and 'A'-'F'.
  30The default is ascii.
  31
  32Device Operation
  33----------------
  341.      Turn on the device:
  35        echo 1 > /sys/bus/usb/.../powered
  362.      Set the device's mode:
  37        echo $mode_msb > /sys/bus/usb/.../mode_msb
  38        echo $mode_lsb > /sys/bus/usb/.../mode_lsb
  393.      Set the textmode:
  40        echo $textmode > /sys/bus/usb/.../textmode
  414.      set the text (for example):
  42        echo "123ABC" > /sys/bus/usb/.../text (ascii)
  43        echo "A1B2" > /sys/bus/usb/.../text (ascii)
  44        echo -ne "\x01\x02\x03" > /sys/bus/usb/.../text (hex)
  455.      Set the decimal places.
  46        The device has either 6 or 8 decimal points.
  47        to set the nth decimal place calculate 10 ** n
  48        and echo it in to /sys/bus/usb/.../decimals
  49        To set multiple decimals points sum up each power.
  50        For example, to set the 0th and 3rd decimal place
  51        echo 1001 > /sys/bus/usb/.../decimals
  52