User manual

Table Of Contents
Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 722
UG585 (v1.11) September 27, 2016
Chapter 28: System Test and Debug
Figure 28-1 shows the four classes of CoreSight components:
Access and control: DAP, ECT
Trace source: PTM, FTM, ITM
Trace link: Funnel, Replicator
Trace sink: ETB, TPIU
The components are connected by three types of buses/signals:
•Programming
Trigger
•Trace
The CoreSight system interacts with:
CPUs through PTM for debug and trace
•CPUs through ITM for trace
PL through FTM for debug and trace
CPUs through ETB for dumping trace
EMIO/MIO through TPIU for dumping trace
CPUs/JTAG through DAP for programming CoreSight components
28.2.1 Debug Access Port (DAP)
The DAP is the front-end for user access to the Zynq-7000s AP SoC system test and debug
functionalities. It is a CoreSight component of the access and control class, and connects to other
components using the programming bus. DAP provides the user, with two interfaces to access the
CoreSight infrastructure:
External: JTAG, from chip pinout
Internal: APB slave, from the slave interconnect
A debugger can use JTAG to communicate with the CoreSight infrastructure, while software running
on a CPU uses APB through memory-mapped addresses assigned to the CoreSight infrastructure.
The DAP forwards access requests arriving via either interface to the requested CoreSight
component.
In addition, the DAP also has another interface to access subsystems other than CoreSight, on the PS:
Internal: AHB master, to the master interconnect
With AHB, the DAP can forward access requests from JTAG to other subsystems in the PS, subject to
authentication requirements. For example, a debugger can query the value of a location in DDR or
the value of a coprocessor register.
The DAP follows the access model described in ARM Debug Interface v5 Architecture Specification
and ARM Debug Interface v5.1 Architecture Supplement, where JTAG indirectly accesses debug
components and resources by way of registers in the DAP.