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comparison FC-handset-spec @ 65:153b517ccc7a

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FC-handset-spec section 1.7.2: make contrast with MIDI ringtone chips
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 15 Jun 2021 19:57:05 +0000
parents 6b02de926277
children a2857b6c3d87
comparison
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64:6b02de926277 65:153b517ccc7a
514 earpiece physical position seems very uncommon. 514 earpiece physical position seems very uncommon.
515 515
516 1.7.2. Loudspeaker implementation 516 1.7.2. Loudspeaker implementation
517 517
518 The external amplifier chip for driving the 8 ohm loudspeaker will be TI 518 The external amplifier chip for driving the 8 ohm loudspeaker will be TI
519 TPA6203A1, copied from Leonardo schematics and proven good on FCDEV3B. On 519 TPA6203A1, copied from Leonardo schematics and proven good on FCDEV3B. It is a
520 FCDEV3B this amplifier is fed with signal from Iota EAR output, but on the final 520 "dumb" loudspeaker amplifier, as opposed to a much more complex chip that
521 handset and on the Venus development board this amplifier will be fed with 521 combines the loudspeaker amplifier function with a MIDI ringtone player - see
522 signal from Iota AUX output instead. 522 section 1.8. On FCDEV3B this amplifier is fed with signal from Iota EAR output,
523 but on the final handset and on the Venus development board this amplifier will
524 be fed with signal from Iota AUX output instead.
523 525
524 The loudspeaker amplifier has an on/off control by way of a Calypso GPIO; in 526 The loudspeaker amplifier has an on/off control by way of a Calypso GPIO; in
525 order to save battery, this amplifier needs to be off normally, and only turn on 527 order to save battery, this amplifier needs to be off normally, and only turn on
526 when a loudspeaker call is in progress or when a ringtone melody is played. 528 when a loudspeaker call is in progress or when a ringtone melody is played.
527 529