changeset 55:a2ce85275f63

lunalcd[12]/README written
author Mychaela Falconia <falcon@freecalypso.org>
date Wed, 23 Jun 2021 08:23:10 +0000
parents 91798685fd8d
children 680be2e17f00
files lunalcd1/README lunalcd2/README
diffstat 2 files changed, 33 insertions(+), 0 deletions(-) [+]
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+The board project contained in this directory was built in 2020-04 under highly
+adverse political conditions.  It is an LCD carrier board originally built to be
+connected to the expansion interface on the historical iWOW DSK v4.0 Calypso
+motherboard, also compatible with our FC Caramel2 MB built in the later part of
+2020.  The actual LCD module in this design is HaoRan HT020K1QC36S: out of the
+two candidate LCD modules we had evaluated in the FT2232D MCU host bus emulation
+setup back in 2018, this one was a little easier to use mechanically in a quick
+low-effort development board like the one we needed to build in 2020-04.
+
+These HaoRan LCD modules appear to be no longer available (in our 2020 work we
+used the last remaining sample pieces from the batch we got in 2018), but the
+new LCD subsystem board being designed in the lunalcd2 directory (using a
+different LCD module from a new vendor with whom we are engaging in 2021) is
+hoped to be a satisfactory replacement.
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lunalcd2/README	Wed Jun 23 08:23:10 2021 +0000
@@ -0,0 +1,19 @@
+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.