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changeset 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
files FC-handset-spec
diffstat 1 files changed, 6 insertions(+), 4 deletions(-) [+]
line wrap: on
line diff
--- a/FC-handset-spec	Tue Jun 15 19:28:52 2021 +0000
+++ b/FC-handset-spec	Tue Jun 15 19:57:05 2021 +0000
@@ -516,10 +516,12 @@
 1.7.2. Loudspeaker implementation
 
 The external amplifier chip for driving the 8 ohm loudspeaker will be TI
-TPA6203A1, copied from Leonardo schematics and proven good on FCDEV3B.  On
-FCDEV3B this amplifier is fed with signal from Iota EAR output, but on the final
-handset and on the Venus development board this amplifier will be fed with
-signal from Iota AUX output instead.
+TPA6203A1, copied from Leonardo schematics and proven good on FCDEV3B.  It is a
+"dumb" loudspeaker amplifier, as opposed to a much more complex chip that
+combines the loudspeaker amplifier function with a MIDI ringtone player - see
+section 1.8.  On FCDEV3B this amplifier is fed with signal from Iota EAR output,
+but on the final handset and on the Venus development board this amplifier will
+be fed with signal from Iota AUX output instead.
 
 The loudspeaker amplifier has an on/off control by way of a Calypso GPIO; in
 order to save battery, this amplifier needs to be off normally, and only turn on