Tektronix 4000 Series, User Manual

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Acquire the Signal
To trigger on serial or parallel bus conditions, refer to Triggering on Buses. (See page 132, Triggering on Buses .)
NOTE. If you de fi ne a bus to use both analog and digital channels, then the bus decode and the bus waveform display will sample
the analog channels at the same rate and the same record length as the digital channels. At some settings, this rate and record
length are different from the analog channel rate and record length. If an analog channel that is used in a bus is also simultaneously
displayed as an ordinary channel, that display uses the full analog sample rate.
Physical Layer Bus Activity
Oscilloscope waveform traces from channels 1 to 4, channels D15 to D0, and the traces you see when you choose to display a bus
as Bus and Waveforms always show the physical layer bus activity. In the physical layer display, bits that were transmitted earlier
are to the left, and bits that were transmitted later are to the right.
I2C and CAN buses transmit the MSB (most signi fi cant bit) fi rst
SPI buses do not specify a bit order
RS-232 buses transmit the LSB (least signi fi cant bit) fi rst
NOTE. The oscilloscope displays the decode traces and event tables for all buses with the MSB on the left and LSB on the right.
Tektronix 4000 Series Oscilloscopes User Manual 109