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Fix large blacklevel step. Lower 25% of shades are now accessible.

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There is a large step in brightness from level zero to level one.
After experimenting with various ST7789 options, I found that
decreasing VDV to 0x10 (-0.4V) fixes this issue.

The gamma change reduced the average error in brightness, but with the
underlying issue fixed, the gamma change has been reverted.
This commit is contained in:
Riku Isokoski
2022-04-26 13:09:30 +03:00
parent b31fbb4adb
commit 8061822f0c
9 changed files with 16 additions and 14 deletions
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10
src/drivers/St7789.cpp
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@@ -23,7 +23,7 @@ void St7789::Init() {
RowAddressSet();
DisplayInversionOn();
NormalModeOn();
SetGamma();
SetVdv();
DisplayOn();
}
@@ -115,9 +115,11 @@ void St7789::WriteToRam() {
WriteCommand(static_cast<uint8_t>(Commands::WriteToRam));
}
void St7789::SetGamma() {
WriteCommand(static_cast<uint8_t>(Commands::GammaSet));
WriteData(0x04);
void St7789::SetVdv() {
// By default there is a large step from pixel brightness zero to one.
// After experimenting with VCOMS, VRH and VDV, this was found to produce good results.
WriteCommand(static_cast<uint8_t>(Commands::VdvSet));
WriteData(0x10);
}
void St7789::DisplayOff() {