# HG changeset patch # User Mychaela Falconia # Date 1624436590 0 # Node ID a2ce85275f632ae5d08c8c36047e48a2d9716d94 # Parent 91798685fd8d235f1a76015d1695ff44cea7796f lunalcd[12]/README written diff -r 91798685fd8d -r a2ce85275f63 lunalcd1/README --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lunalcd1/README Wed Jun 23 08:23:10 2021 +0000 @@ -0,0 +1,14 @@ +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. diff -r 91798685fd8d -r a2ce85275f63 lunalcd2/README --- /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.