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Serial bus analysis
R&S
®
RTA4000
278
User Manual 1335.7898.02 ─ 08
●
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.
Trigger
The R&S
RTA4000 can trigger on specified parts of UART serial signals:
●
Start bit
●
Frame start
●
A specified symbol
●
Parity errors, and breaks
●
Frame errors
●
A serial pattern at any or a specified position
13.4.2
UART configuration
The correct setup of the protocol parameters and the threshold is the condition for
decoding the signal.
To set up and decode a UART signal
1. Press the [Protocol] key in the Analysis area of the front panel.
2. Select the "Bus Type" = UART.
3. Select the bus that you want to use: B1, B2, B3 or B4.
Bus B2 is only available if the TX line is set to "None" in the "Configuration" dialog.
4. Select "Configuration".
5. Select the "TX / RX / Source", the channel to which the input signal is connected.
6. Set the threshold. Use one of the following methods:
● Tap "Find Threshold". The instrument evaluates the signal and sets the thresh-
old.
● Enter the threshold value in the numeric field.
7. Set the other signal parameters according to the signal characteristics.
8. In the "Bus" menu, enable "Decode".
UART / RS232 (option R&S
RTA-K2)