[Discuss-gnuradio] simple: gr.add_ff usage?

[cswiger]

Hi - An older example showed adding two signals + DC (dial tone) thusly:

    fg = gr_FlowGraph ()

    # ``US Dial Tone'' 350 Hz + 440 Hz
    sig1 = VrSigSource_float (sample_rate, VR_SIN_WAVE, 350, 0.20)
    sig2 = VrSigSource_float (sample_rate, VR_SIN_WAVE, 440, 0.20)

    one = VrSigSource_float (sample_rate, VR_DC_WAVE, 0, 1.0)

    # sum = 1 + sig1 + sig2

    sum = GrAddFF ()
    fg.connect (sig1, sum)
    fg.connect (sig2, sum)
    fg.connect (one, sum)

    amp = VrAmpFF (carrier_ampl)
    fg.connect (sum, amp)

Which makes sense. But When I try it out like this:

    fg = gr.flow_graph ()
    src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl)
    src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl)
    sum = gr.add_ff ()
    dst = audio.sink (sampling_freq)
    fg.connect ( src0, sum )
=>    fg.connect ( src1, sum )
    fg.connect ( sum, dst)


I get "destination endpoint already in use" on the second fg.connect.
Has usage changed also? Just experimenting... It's slowly making sense.

--Chuck
kb4new