printf Debugging

Use printf when you want to print during the simulation.

• Note: this will print at the end of the cycle so you’ll see the values on the wires after the cycle has passed.
• Use printf(p"This is my text with a $var\n") to print Chisel variables. Notice the “p” before the quote!
• You can also put any Scala statement in the print statement (e.g., printf(p"Output: ${io.output})).
• Use println to print during compilation in the Chisel code or during test execution in the test code. This is mostly like Java’s println.
• If you want to use Scala variables in the print statement, prepend the statement with an ‘s’. For example, println(s"This is my cool variable: $variable") or println("Some math: 5 + 5 = ${5+5}").
• print statements will be carried over to generated verilog as $fwrite()