diff lunalcd2/README @ 55:a2ce85275f63

lunalcd[12]/README written
author Mychaela Falconia <falcon@freecalypso.org>
date Wed, 23 Jun 2021 08:23:10 +0000
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+Formike KWH020ST23-F01 is a candidate LCD module being considered for our
+FreeCalypso Libre Dumbphone dream handset.  Prior to building the actual
+handset, we will need to build our FC Venus development board, and prior to
+starting the design of this Venus board, we are going to test the proposed LCD
+module in our currently existing Luna environment.  The modular LCD subsystem
+board being designed in this directory is intended to be a drop-in replacement
+for our previous Luna LCD board from 2020-04 (lunalcd1 directory), to be
+connected to the same Caramel/C2 motherboards, with the resulting system
+configuration still being Luna (not Venus).
+
+In addition to changing out the LCD module, the backlight driver circuit is
+being changed to the MAX1916-based one described in FreeCalypso Handset
+Specification section 1.4.4, with a set of DIP switches selecting different LED
+currents - the intent is to find appropriate LED currents for the different
+display brightness modes that will be needed in the actual handset.  A current
+measurement resistor is also being inserted in the LCD (not backlight) power
+supply path - we will be exercising the LCD controller/driver chip's power-
+saving sleep modes, and we need to be sure that they actually reduce the 2.8V
+supply current draw as expected.