From 8061822f0cba9caa9d957b85a8284ab3120aaf3e Mon Sep 17 00:00:00 2001
From: Riku Isokoski <riksu9000@gmail.com>
Date: Tue, 26 Apr 2022 13:09:30 +0300
Subject: Fix large blacklevel step. Lower 25% of shades are now accessible.

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.
---
 src/drivers/St7789.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/drivers/St7789.h')

diff --git a/src/drivers/St7789.h b/src/drivers/St7789.h
index 1317abe2..a2f10447 100644
--- a/src/drivers/St7789.h
+++ b/src/drivers/St7789.h
@@ -43,7 +43,7 @@ namespace Pinetime {
       void NormalModeOn();
       void WriteToRam();
       void SetAddrWindow(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1);
-      void SetGamma();
+      void SetVdv();
       void WriteCommand(uint8_t cmd);
       void WriteSpi(const uint8_t* data, size_t size);
 
@@ -53,7 +53,6 @@ namespace Pinetime {
         SleepOut = 0x11,
         NormalModeOn = 0x13,
         DisplayInversionOn = 0x21,
-        GammaSet = 0x26,
         DisplayOff = 0x28,
         DisplayOn = 0x29,
         ColumnAddressSet = 0x2a,
@@ -63,6 +62,7 @@ namespace Pinetime {
         VerticalScrollDefinition = 0x33,
         VerticalScrollStartAddress = 0x37,
         ColMod = 0x3a,
+        VdvSet = 0xc4,
       };
       void WriteData(uint8_t data);
       void ColumnAddressSet();
-- 
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