Display space character with DCV command to clear screen, but this command is
very slow. I tested filling whole 160x128 area with 8x16 character by DCV16
command, it took 540msec.
This is the worst case, but display refresh period has extended to 600ms
for safety.
To clear screen, use BOXF command instead. And, reduced issuing DCV command.
HobbyTronics TFT Shield has discontinued, here is a replacement TFT module
that can be controlled from UART.
Different from TFT Shield, it cannot display figures that stored in
micro SD card. So appearance is simplified like OLED.
Surenoo module sometimes ignores display commands (in busy stuation?),
this driver buffers display status and refresh at clockInt().