Multicore Devices

Some devices have more than one JTAG core inside them, and so have more than one BSDL file assigned to them. XJTAG terms such devices Multicore Devices.

Categorising

Multicore devices are categorised like any other JTAG device on the JTAG chain screen. When configuring the device, all that is required is to select that the device contains multiple cores and then add the BSDL files for those cores.

MCD Files

Within the XJTAG project, the definition of each multicore device is stored in its own .mcd file. An existing definition can be imported into a project.

Referencing cores

Typically a multicore device will be referenced as a whole. However, there are some circumstances where the individual cores need to be referenced, for example, in XJEase when running SVF or STAPL files or in raw JTAG statements. Each core within a device is named and the name of the core can be used in these cases along with the device reference: IC2.core0 or Board.IC2.core0.

Analyser

Multicore device cores are displayed as separate devices in XJAnalyser and on the Analyser screen. This is necessary since the cores can be controlled separately, running in different modes.

Multiple TAPs

Many multicore devices will have their cores all connected in a single chain within the device and so have a single TAP (i.e. a set of JTAG pins: TDO, TDI, TCK, TMS and optionally nTRST). However, some devices may have multiple TAPs and so have multiple chains within them. Since the JTAG chain screen edits a single JTAG chain at a time, when handling such a device, you must configure each chain or TAP individually.