Xilinx UG129 manual Input/Output Ports, 5Example of pBlazIDE Dsout Directive

R

Chapter 11: Assembler Directives

specifies a text file that records the result of any output operations to this during instruction set simulation. Figure 11-5provides an example.

;pBlazIDE syntax to define a write-only output port

;output_port_name DSOUT <port_id#>[, “<output_file_name>”]

LEDs	DSOUT	$01, “output_values.txt”
writeport	DSOUT	$1E

Figure 11-5:Example of pBlazIDE DSOUT Directive

The values recorded in the optional output file are always written as hexadecimal values.

During instruction set simulation, pBlazIDE displays the write-only output port as shown in Figure 11-6. Output ports are write-only and cannot be modified from the graphical interface.

Figure 11-6:The pBlazIDE DSOUT Directive Defines an Output Port

The DSOUT directive is also useful to create stimulus files later read using DSIN directives in another pBlazIDE application program. For example, to create a stimulus input file containing incrementing data values, create a quick pBlazIDE program that increments a value and writes the value to an output port declared using a DSOUT directive, complete with file specification. Once the program completes, this resulting file can be read by another pBlazIDE program during instruction set simulation using the DSIN directive.

Input/Output Ports

The DSIO directive defines the name and the port address (or port identification number) for an output port. However, the DSIO directive differs from the DSOUT directive in that the PicoBlaze microcontroller can also read DSIO output values. The DSIO directive models an output port that connects to both the PicoBlaze microcontroller’s IN_PORT and OUT_PORT ports and has the same port address for input and output operations. An optional field specifies a text file that records the result of any output operations to this during instruction set simulation. Figure 11-7provides an example.

;pBlazIDE syntax to define a readable output port

;input_output_port_name DSIO <port_id#>[“<output_file_name>”]

mailbox	DSIO	$02, “mailbox_out.txt”
readwrite	DSIO	$1D

Figure 11-7:Example of pBlazIDE DSIO Directive

The values recorded in the optional output file are always written as hexadecimal values.

78	www.xilinx.com	PicoBlaze 8-bit Embedded Microcontroller
		UG129 (v1.1.2) June 24, 2008