pphelloworld
pphelloworld is the smallest built-in live output-toggle smoke test.
It programs a two-state repeating sequence that toggles all output bits between 0xffffffff and 0x00000000.
This command is intentionally broad and continuous: it drives all 32 outputs and does not stop the FPGA replay when the process exits. Use the finite First output chapter for initial wiring checks.
When to use it
Use pphelloworld when you want a minimal end-to-end check that:
- the basic streamer path is alive
- outputs are toggling at the expected clock-derived rate
- your scope or logic analyzer can see activity without setting up a more complex workflow
Common options
-core_pll-int_pll-int_clk
The PLL options configure the candidate clocks. Use -int_clk when the test must explicitly select the internal streamer-clock path; programming -int_pll alone does not change a previously selected external path.
Examples
Run with the default clock settings:
pphelloworld
Run at an explicitly selected 10 MHz internal/core clock point:
pphelloworld -core_pll 10M -int_pll 10M -int_clk
What to expect
The command loads a small sequence with two stored elements and a replay instruction, then forces triggering.
After startup, all outputs toggle with frequency:
streamer_clk / 1000
At the default 100 MHz streamer clock, that is 100 kHz.
This makes pphelloworld useful for checking output toggling and the expected output rate on a scope.
After the test, run ppreset -i 0x0. The reset leaves the outputs actively driven low. Before connecting another driver, power down or release the bidirectional pins with ppread -oe 0 -hard-timeout 100ms.