SVF Dateien

Über SVF kodierte Text-Dateien können JTAG Test-Pattern definiert werden.

Eine SVF-Datei enthält dabei eine Liste von Befehlen (oder auch Kommentaren). Hier ein Beispiel:

SDR 64 TDI(0) TDO(0123456789ABCDEF) MASK(0FFFFFFFFFFFFFFF);

Dieser Befehl erzeugt 64 Taktzylken, scanning in 64 zeros and expecting to read 0x0123456789ABCDEF out, with the mask of 0FFFFFFFFFFFFFFF indicating that the first 4 bits are not significant, but all the rest are.

Headers and trailers can also be set up, enabling you to target a specific device, or set of devices, in the JTAG chain without having to consider the other devices in the chain at each step.

The complete list of SVF commands is as follows.

ENDDR 	Specifies default end state for DR scan operations.
ENDIR 	Specifies default end state for IR scan operations.
FREQUENCY 	Specifies maximum test clock frequency for IEEE 1149.1 bus operations.
HDR 	(Header Data Register) Specifies a header pattern that is prepended to the beginning of subsequent DR scan operations.
HIR 	(Header Instruction Register) Specifies a header pattern that is prepended to the beginning of subsequent IR scan operations.
PIO 	(Parallel Input/Output) Specifies a parallel test pattern.
PIOMAP 	(Parallel Input/Output Map) Maps PIO column positions to a logical pin.
RUNTEST 	Forces the IEEE 1149.1 bus to a run state for a specified number of clocks or a specified time period.
SDR 	(Scan Data Register) Performs an IEEE 1149.1 Data Register scan.
SIR 	(Scan Instruction Register) Performs an IEEE 1149.1 Instruction Register scan.
STATE 	Forces the IEEE 1149.1 bus to a specified stable state.
TDR 	(Trailer Data Register) Specifies a trailer pattern that is appended to the end of subsequent DR scan operations.
TIR 	(Trailer Instruction Register) Specifies a trailer pattern that is appended to the end of subsequent IR scan operations.
TRST 	(Test ReSeT) Controls the optional Test Reset line.

Folgende Tools können SVF-Dateien ausführen: