diff options
Diffstat (limited to 'decoders/usb/__init__.py')
| -rw-r--r-- | decoders/usb/__init__.py | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/decoders/usb/__init__.py b/decoders/usb/__init__.py index 1a16f8f..313c495 100644 --- a/decoders/usb/__init__.py +++ b/decoders/usb/__init__.py @@ -21,6 +21,8 @@ ''' USB (low-speed and full-speed) protocol decoder. +Electrical/signalling layer (USB spec, chapter 7): + USB signalling consists of two signal lines, both driven at 3.3V logic levels. The signals are DP (D+) and DM (D-), and normally operate in differential mode. @@ -41,6 +43,8 @@ Data is transferred at a rate of 1.5Mbit/s (low-speed) / 12Mbit/s (full-speed). The SE0 transmitted to signal an end-of-packet is two bit intervals long (low-speed: 1.25uS - 1.50uS, full-speed: 160ns - 175ns). +Protocol layer (USB spec, chapter 8): + Bit/byte ordering: Bits are sent onto the bus LSB-first. Multibyte fields are transmitted in little-endian order (i.e., LSB to MSB). |