Jtag Master (Jtagm); Development Trigger Semaphore (Dts); Debug Over Can - STMicroelectronics SPC572L series Reference Manual

Calibration and Debug
Related module

JTAG Master (JTAGM)

Development Tool Semaphore (DTS)
11.3.1 JTAG Master (JTAGM)
The JTAG Master (JTAGM) is a module that is able to act as JTAG master inside the device.
The module has a parallel interface that can exchange data via customer software.
The data transferred to this module is transformed to produce TCK, TMS, TDI and TRST
outputs and to accept TDO inputs. The module is connected in the device to allow these five
signals to connect to the JTAGC as if the JTAG data was coming from an external tool.
JTAGM generates all required JTAG scan chains to allow software and high speed serial
communication access to all JTAG mapped resources.
11.3.2

Development Trigger Semaphore (DTS)

The Development Trigger Semaphore (DTS) module enables software to signal an external
tool by driving a persistent (affected only by reset or an external tool) signal on an external
device pin. There are a variety of ways this module can be used, including as a component
of an external real-time data acquisition system.
Note: When used as a component of a triggered data acquisition system, Nexus read/write access
is via the JTAG interface of the Nexus debug port and is different than the data acquisition
protocol defined in the IEEE-ISTO 5001-2003 or IEEE-ISTO 5001-2011 Nexus standards,
which use the Nexus Auxiliary port.
11.4

Debug over CAN

As well as supporting debug via the JTAG interface, the device supports the use of a CAN
interface for debug. This allows debug of application hardware where access to the
dedicated JTAG interface signals is not easily available. The debug over CAN mechanism is
intended to provide basic debug functionality with some reduction in bandwidth and features
compared to use of the dedicated JTAG interface.
Use of the CAN interface for debug purposes requires the use of some M_CAN, eDMA, and
JTAGM resources. Some initialization of these resources via software is required, but once
this initialization has completed, debug over CAN is possible without any further software
overhead.
As the debug over CAN scheme generates internal JTAG messages based on received
CAN data, all JTAG clients and included debug resources are accessible. Basic device trace
capability is also possible by configuring the device trace hardware to stream to a device
overlay/trace RAM, which can be read later using debug over CAN.
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Table 88. Reference links to related information
DocID027809 Rev 4
Reference
Chapter 62: JTAG Master (JTAGM)
Chapter 64: Development Trigger Semaphore (DTS)
RM0400