RGMII
MAC RX/TX
Synchronous CAPTURE
WITH 16802A AGILENT LOGIC ANALYZER
Pascal GRISON Application Engineer
Objectives
• Define a Logic Analyzer Configuration that
would enable Synchronous capture of RGMII
MAC interface
• Ideally Capture simultaneously TX and RX
RGMII MAC Interface details
Bidirectional
Full Duplex
125MHz Clock (for GbE)
TX Side
TXC (Dual Edge Clocking)
TD[4] TD0 TD1 TD2 TD3
D3..DO sent on Rising TXC
D7..D4 sent on falling TXC
TX_CTL
TX_EN sent on Rising TXC
TX_ERR sent on falling TXC
RX Side
RXC (Dual Edge Clocking)
RD[4] RD0 RD1 RD2 RD3
D3..DO sent on Rising RXC
D7..D4 sent on falling RXC
RX_CTL
RXDV sent on Rising RXC
RXERR sent on falling RXC
Capture TX Transactions
Need Synchronous Sampling: State Mode
Need Double Edge Clocking:
->State Sampling at 250MHz on 125MHz Clock
-> Logic Analyzer
-> Demux Mode to rebuild Data[8]
RGMII TX Timings
TXD[3:0] & TXEN will be Clocked on Rising edge of TXC
TXD[7:4] & TXERR will be Clocked on Falling edge of TXC
-> We need to use Both Edges Clocking (DEMUX Mode)
Demux Sampling Mode?
2) -> TXCK FallingEdge
1) -> TXCK Rising Edge
In the Demultiplex state sampling clock mode, you can demultiplex data being probed by one pod into
the logic analyzer memory that is normally used for two pods. Demultiplex mode uses the master
and slave clocks to demultiplex the data.
When the slave clock occurs, data captured on the pod is saved into the slave latch for the other pod
in the pod pair. Then, when the master clock occurs, data captured on the pod, as well as the slave
latch data, are saved in logic analyzer memory. As with master/slave mode, if multiple slave clocks
occur before the next master clock, only the most recently acquired slave data is saved into logic
analyzer memory.
Configure DEMUX Sampling
Config Logic Analyzer as DEMUX STATE on TX CLOCK
Rising Edge is Salve Clock and Happend First
Falling Edge is Master Clock and Happend Second
Master Clock Event activate Storage of one State Sample
Up to 16M available (with Option 32)
Configure Bus SETUP
Config of Logic Analyzer buses
TXCK
TXDATA as 8 bit bus
TXDATA[3:0] & TXEN will be Clocked on Rising edge of TXC
TXDATA[7:4] & TXERR will be Clocked on Falling edge of TXC
FULL DATA[7:0] + TXEN +TXERR will be stored in one memory space in logic Analyzer every clock Cycle
Up to 16M TX Packet Can be Acquired (with option 32M)
Overview of Logic Analyzer for TX DEMUX
Current Config is the following:
One Analyzer configured as one
State Acquisition system to
Demux and Acquire TX
Packets
What About RX?
We Need to Acquire TX & RX Packets
RX Clock behave in similar dual edge as TX Clock
RGMII RX Timings
RXC is derived from received Ethernet Packets (Asynchronous from TXC)
RXD[3:0] & RXDV will be Clocked on Rising edge of TXC
RXD[7:4] & RXERR will be Clocked on Falling edge of TXC
-> We need to use Both Edges Clocking (DEMUX Mode)
How to Capture RX Packets
RX Clock is Asynchronous to TX
Clock
RXDATA and RX_CTL are muxed
TX Clock CANNOT be used to
Acquired RX Data
Need to define two independant
State Demux Acquisition
System, one based on TXClock
one on RXClock…
Can we do this on a Single Logic
Analyzer?
Now Let’s Split Your 68Ch Logic Analyzer
into Two 34Ch Logic Analyzers
Agilent Logic Analyzers has unique capability to split themselves in Two!
We now dispose of Two Independant
Logic Analyzers in one
Independant Channel Setup
Independant Salmpling Mode
Independant Clocking
Independant Triggers
Independant Listing/Waveforms
But Also Capable of
Master/Slave Triggering
Correlated Mesure thanks to
Independant Timestamps
Common Listing/Waveforms Capability
Complete TX/RX Demux
Synchonous sampling System Overview
TX Demux Master Trigger
RX Demux Trigged from TX Trigger
Common TX/RX Listing
Common TX/RX Waveforms
Simultaneous 4GSa/s Timing
oversampling (TimingZoom)
available (capture 16µs around
trigger)
Exemple of RGMII TX/RX Listing
Demo Offline Data / Not real
RGMII Capture
Scope –Logic Analyzer
Time Correlated Measurements
Use Logic analyzer to trigger on RGMII Sequence of TX or RX Packets to Trigger Oscillosocpe
Use Glitch or serial Trigger on Oscillosocpe to Trigger Logic analyzer and find matching RGMII Packet
Get ALL Analog + Digital signals Displayed on single display
Save ALL Analog + Digital signals Displayed on single file for post processing or Off-Line analysis
Compatible with All current Agilent Scope and Logic Analyzers
Easy to Setup
Lan based for data transfert & control
2 BNC Cables from Triggers with autodeskew capability
Automatic Fast waveform transfert from Scope to Logic Analyzer
Markers correlated between instruments
Exemple of Measure on DAC
Digital inputs correlated with Analog Output
Questions & Answers?