10 Dec 2015: Libre Laptop STM32F072 and HX8357D SPI LCD success
Talking to the Adafruit HX8357D 480x320 SPI-based LCD has proven successful and reliable, with the introduction of some RC stabilising filters on the SPI clock and CS lines, as well as a reduction in the anticipated speed delay used in the SPI bit-banging routines.
The HX8357D LCD from Yunlea differs from the setup of the Adafruit HX8357D LCD in that firstly it has a capacitive panel glued to it but secondly in that the "Data/Command" hard line is not provided, such that a 9-bit write must be carried out (and an 8-bit read). The 9th bit is used to select whether the remaining 8 bits are data or command, however reads are always simply 8 bit. Setting up the STM32F072 SPI interface to carry out these weird 9 to 8 bit changes proved sufficiently awkward as to make it preferable on a first software pass to use bit-banging.
Below can be seen an image of the LCD during its reset phase, where the bottom lines have been cleared with a memory write (to black). The next phase will be to test PCB2, however this first requires modification of the tracks to insert a 22 ohm resistor into the clock line and to put a 22pf capacitor across it to ground. More to follow.