Specifications

36
Subject to change without notice
Pressing the soft menu key DATA will open a submenu which
allows to enter data in addition to the address.
Fig. 12.6: I
2
C data Trigger menu
It is possible to trigger on a maximum of 24 bits (3 bytes) of
data which may have an offset from 0 to 4095 with respect to
the address. In order to select an offset, press BYTE OFFSET.
In most cases the offset will be zero if it is desired to trigger on
the maximum of 24 rst bits following the address. Use the soft
menu key NUMBER OF BYTES in order to select whether 1, 2 or
3 bytes of data should be entered. The entry may be binary or
hexadecimal which is selected with the soft menu key INPUT.
If binary entry was selected, the individual bits may be chosen
with the soft menu key BIT and the universal knob. With the soft
menu key DEFINITION you can choose for each bit whether it
shall be 1, 0 or X (don’t care). If hexadecimal entry was chosen,
the soft menu key VALUE and the universal knob are used to
dene the value of each byte. Th soft menu key BYTE is used
to switch from byte 1 to byte 2 andto byte 3 (if the byte number
chosen was 3). In the display window of the trigger conditions
the presently active byte will be framed in green.
By pressing the MENU OFF key three times all menus will be
closed, and the oscilloscope will trigger on the address and
data entered.
12.4 SPIbus
The SPI bus was developed by Motorola (today: Freescale),
however, it is not formally standardized. In general, it is a bus
with a clock and data lines and a select line. If only one master
and one slave are present, the select line may be deleted; this
is also calles SSPI (Simple SPI).
12.5 SPIbusdenition
For the correct decoding of a SPI bus some settings are re-
quired. The rst denition pertains to the type of bus: whether
it is a 2-wire (without chip select) or a 3-wire system (with chip
select). This is done in the bus conguration menu when selec-
ting the bus type: for a 2-wire system choose the entry SSPI, for
a 3-wire system SPI. Subsequently open the SPI conguration
menu by pressing the key CONFIGURATION.
The top soft menu key SOURCE is used to dene the respective
digital channels for chip select, clock and data. (In case of a
2-wire system choose the dead time instead of a chip select
source.) Pressing this soft menu key will present one of the three
choices (the selected one will be shown with a blue background),
in the menu which will open, use the universal knob to select
the logic channel.
The third soft menu key also allows (in addition to linking the
inputs to the signals) the following settings:
CS: Chip select high or low active, the standard
is low active
CLK: data will be stored with rising or falling slope,
rising is the standard
DATA: high or low active, high is the standard
The soft menu key BIT ORDER denes whether the data of the
messages shall start with the MSB or the LSB.
The soft menu key WORD SIZE is used to set the number of
bits of a message, use the universal knob to select any number
from 1 to 32.
12.6 SPIbustriggering
Following the bus conguration the trigger conditions have
to be dened in order to be able to trigger on various events.
Press the key TYPE in the TRIGGER area of the front panel and
select the soft menu key SERIAL BUSES. Subsequently press
the key SOURCE in the TRIGGER area and select the SPI bus.
(It will only show up if it was previously dened.) Pressing the
key FILTER in the TRIGGER area will present all possible trig-
ger options. Triggering is possible on the FRAME START, the
FRAME END and in a preselected BIT. (Press the soft menu key
Serial bus analysis
Fig. 12.8: SPI trigger menu
Fig. 12.7: Menu for the SPI bus denition