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Serial Bus Analysis

❙

CLK:

Data will be stored with rising or falling slope (rising

slope is the default setting)

❙

DATA:

Data high or low active (high active is the default

setting)

Certain portions of the SPI/SSPI messages will be displayed
in color to distinguish between the different elements:

❙

White

Start / End of complete frame

❙

Red

Incomplete word that is not completely

contained in the acquisition; change the

horizontal scale or move the“Time

Reference“ to get a longer acquisition

❙

Cyan

Decoded words

You can use the soft menu key BIT ORDER to determine if
the data of each message starts with the MSB (most sig-

nificant bit) or the LSB (least significant bit). The soft menu

key WORD SIZE allows you to select via universal knob
how many bits are included per message. You may select
any value between 1 and 32 bits.

13 .5 .2 SPI / SSPI BUS Triggering

After the SPI/SSPI

BUS configuration, it will be possible

to trigger on various events. Press the TYPE button in the
TRIGGER section of the control panel and choose the soft
menu key SERIAL BUSES. Then press the SOURCE button
in the TRIGGER section and choose SPI Bus. This will only

be available if it was configured earlier. Press the FILTER

button in the TRIGGER section of the control panel to list
all available SPI trigger conditions. The following trigger

conditions can be defined:

❙

FRAME START:

Sets the trigger event on the start of the

frame. The frame starts when the chip select (CS) signal
switches to the selected active mode.

❙

FRAME END:

Sets the trigger event on the end of the

frame. The frame ends when the chip select (CS) signal
switches from the selected active to the inactive mode.

❙

BIT:

Selects the trigger time to the set bit within the set

bit sequence with the universal knob in the CURSOR/
MENU section. You can also enter a numeric value to
determine the desired bit number (KEYPAD button).

❙

SER . PATTERN:

Use the soft menu SER. PATTERN to

define a specific bit sequence within the frame which

start the trigger event. The soft menu key BIT OFFSET

Fig. 13.9: Menu for the definition of a

SPI bus

allows you to select the first bit of the predefined bit

sequence within the frame. The bits in front of it have no
impact on the trigger event (for instance, if the bit offset =
2, bit 0 and bit 1 after CS will be ignored and the pattern
begins with bit 2). You can select a value between 0 and
4095 via universal knob or enter it numerically (KEYPAD
button). The soft menu key NUMBER OF BITS allows you
to select how many bits will be analyzed for the trigger
condition. You can select a value between 1 and 32 bit via
universal knob. The serial bit sequence (PATTERN INPUT)
can be entered as binary or hexadecimal value. If you
choose the binary input, the soft menu key SELECT BIT
and the universal knob allow you to select which
individual bits within the data are to be edited. The option
STATE allows you to assign a logic state to each bit (High
= H = 1, Low = L = 0 or X = don’t care). The state X

defines any state. If you choose the hexadecimal input,

the soft menu key VALUE and the universal knob allow
you to set the value for the respective nibble (4 bit). If the
input is hexadecimal, only the entire nibble can be set to
X. Use the soft menu key SELECT NIBBLE to toggle
between nibbles. The active nibble will be marked with a
green border in the display window of the trigger
condition.

Press the MENU OFF button three times to close all
menus, and the oscilloscope will trigger on the set bit

sequence. For measurements without measuring object

please refer to chapter 10.2.5.

13 .5 .3 SPI/SSPI BUS Table

Fig. 13.10: Example SSPI BUS table

Tab. 13.3: Content of the SPI/SSPI BUS table

Column

Description

Start Time

Time of frame start in relation to the trigger point

Length

Number of words in the frame