ILA Cross Trigger - 2023.2 English

Vivado Design Suite User Guide: Programming and Debugging (UG908)

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2023.2 English

ILA Cross Triggering feature enables cross triggering between ILA cores, and between ILA cores and a processor for example, AMD Zynq™ 7000 SoC. This feature is useful for when you want to trigger between two ILA cores that are in different clock domains or perform hardware/software cross triggering between a processor and an ILA core.

For using cross trigger feature, at core generation time, you should configure the ILA core to have dedicated trigger input ports (TRIG_IN and TRIG_IN_ACK) and dedicated trigger output ports (TRIG_OUT and TRIG_OUT_ACK). If you want to use the ILA trigger input or output signals, you must use the HDL instantiation method of adding ILA cores to your design.

Figure 1. ILA Cross Trigger Feature

TRIG_OUT_ACK signal is an indication to the ILA core (another ILA, user design, or processor) that TRIG_OUT is properly received and causes the ILA to lower the TRIG_OUT signal on receiving TRIG_OUT_ACK.

In other words, TRIG_OUT remains HIGH until TRIG_OUT_ACK is available. If TRIG_OUT_ACK signal is tied to LOW, TRIG_OUT remains HIGH until the user re-arms the ILA. Only the TRIG_OUT goes LOW. You can rearm the ILA if TRIG_OUT_ACK is tied to LOW.

A typical cross trigger setup is illustrated in the following image where ILA2 cross triggers into ILA1. The TRIG_OUT signal of ILA2 is connected to the TRIG_IN signal of ILA1. The TRIG_IN_ACK signal of ILA 1 is connected to the TRIG_OUT_ACK signal of ILA2.

(ILA 2) trig_out  -> (ILA 1) trig_in 
(ILA 1) trig_in_ack -> (ILA 2) trig_out_ack 
Figure 2. Typical Cross Trigger Setup

Figure 3. ILA Cross Trigger Timing

  • It is assumed that the logic driving the trig_in port is synchronous to the ILA clk.
  • It takes 1 clk cycle for the trig_in_ack signal to get asserted after trig_in is asserted.
  • It takes 9 clk cycles for the trig_out signal to get asserted when trig_in is used or trigger condition is met.
  • The trig_in_ack and trig_out_ack signals go low only when trigger signals are de-asserted.

For a detailed tutorial that covers using the Cross Trigger feature between the FPGA fabric and the Zynq 7000 SoC processor, see the Vivado Design Suite Tutorial: Embedded Processor Hardware Design (UG940).