Rohde & Schwarz R&S RTB2000, Руководство пользователя, Страница: 221 / 609

Serial bus analysis
R&S
®
RTB2000
221 User Manual 1333.1611.02 ─ 11
12.2 SPI bus (option R&S RTB-K1)
● The SPI protocol ................................................................................................... 221
● SPI configuration ...................................................................................................222
● SPI trigger ............................................................................................................. 225
● SPI decode results ................................................................................................228
12.2.1 The SPI protocol
A 4-channel instrument is required for full support of the SPI protocol, or the MSO
option R&S
RTB-B1.
The Serial Peripheral Interface SPI is used for communication with slow peripheral
devices, in particular, for transmission of data streams.
Main characteristics of SPI are:
●
Master-slave communication
●
No device addressing; The slave is accessed by a chip select, or slave select line.
●
No acknowledgement mechanism to confirm receipt of data
●
Duplex capability
Most SPI buses have four lines, two data and two control lines:
●
Clock line to all slaves (SCLK)
●
Slave Select or Chip Select line (SS or CS)
●
Master data output, slave data input (MOSI or SDI)
●
Master data input, slave data output (MISO or SDO)
When the master generates a clock and selects a slave device, data may be transfer-
red in either or both directions simultaneously.
Figure 12-3: Simple configuration of SPI bus
The data bits of a message are grouped by following criteria:
●
A word contains a number of successive bits. The word length is defined in the pro-
tocol configuration.
●
A frame contains a number of successive words, at least one word.
For SPI buses, the R&S RTB2000 provides the following trigger possibilities:
●
On frame start
●
On frame end
●
On a specified bit in the message
●
On a serial pattern at a specified position
SPI bus (option R&S RTB-K1)