User manual

Protocol Analysis
R&S
®
RTO
278User Manual 1316.0827.02 ─ 06
Example:
In the figure above, the first three frames contain two words each. The fourth frame is
incomplete, only one word of the frame was recognized
SCPI commands:
● BUS<m>:SPI:FRAMe<n>:DATA on page 671
● BUS<m>:SPI:FCOunt on page 671
● BUS<m>:SPI:FRAMe<n>:STATus on page 672
● BUS<m>:SPI:FRAMe<n>:STARt on page 672
● BUS<m>:SPI:FRAMe<n>:STOP on page 672
● BUS<m>:SPI:FRAMe<n>:WCOunt on page 673
● BUS<m>:SPI:FRAMe<n>:WORD<o>:STARt on page 673
● BUS<m>:SPI:FRAMe<n>:WORD<o>:STOP on page 674
● BUS<m>:SPI:FRAMe<n>:WORD<o>:MISO on page 674
● BUS<m>:SPI:FRAMe<n>:WORD<o>:MOSI on page 674
10.4 UART / RS232
10.4.1 The UART / RS232 Interface
The Universal Asynchronous Receiver/Transmitter UART converts a word of data into
serial data, and vice versa. It is the base of many serial protocols like of RS-232. The
UART uses only one line, or two lines for transmitter and receiver.
Data transfer
The data is transmitted in words, also referred to as symbols or characters. Each word
consists of a start bit, several data bits, an optional parity bit, and one or more stop bits.
Several words can form a package, or frame. The end of a package is marked with a
reserved word or by a pause between two words.
[Data8]
[Parity]
Stop[Data7][Data6][Data5]
Data4Data3Data2Data1Data0
Start
Fig. 10-8: Bit order in a UART word (symbol)
●
The start bit is a logic 0.
●
The stop bits and the idle state are always logic 1.
The UART protocol has no clock for synchronization. The receiver synchronizes by
means of the start and stop bits, and the bit rate that must be known to the receiver.
UART / RS232