From ff7240220b90d0ccbf33d0f4fa8f95a3448c742d Mon Sep 17 00:00:00 2001
From: Federico Terraneo <fede.tft@miosix.org>
Date: Sun, 6 Feb 2022 17:11:34 +0100
Subject: [PATCH] Improved display_er_oledm024 power consumption
---
.../display_er_oledm024.cpp | 31 +++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)
diff --git a/_examples/display_er_oledm024/display_er_oledm024.cpp b/_examples/display_er_oledm024/display_er_oledm024.cpp
index f9b2238..66041e7 100644
--- a/_examples/display_er_oledm024/display_er_oledm024.cpp
+++ b/_examples/display_er_oledm024/display_er_oledm024.cpp
@@ -130,9 +130,36 @@ DisplayErOledm024::DisplayErOledm024() : DisplayGeneric1BPP(128,64)
delayUs(100);
//VCC=13.4V VCOMH=10.4V IREF~11uA SPI_fmax=10MHz
+ /*
+ * Power save mode reduces frame rate and precharge time to reduce current
+ * consumption from the VCC side. Power consumption from the VDD side is
+ * < 100uA and thus negligible.
+ * Measured current [mA] as a function of #pixel active
+ * pixel_on default_current power_save_current
+ * 0 0.70 0.49 (off current)
+ * 128 1.23 0.85
+ * ...
+ * 15*128 6.88 4.98
+ *
+ * Further tried to reduce scanlines to 16 with
+ * cmd(0xd5); cmd(0x03); // Oscillator 0x0, /4 (75Hz)
+ * cmd(0xa8); cmd(15); // Number of rows 16
+ * and got off current down to 0.15mA but per pixel current significantly
+ * increased and bug in cmd(0x81) set brightness did not allow to correct
+ */
+ #define POWER_SAVE //Active by default
+
+ #ifndef POWER_SAVE
+ const unsigned char oscCfg=0xa0; // 120Hz refresh rate
+ const unsigned char prcgCfg=0x25;// Precharge phase2=2 phase1=5
+ #else //POWER_SAVE
+ const unsigned char oscCfg=0x00; // 78Hz -30% off current 0.7 -> 0.48mA
+ const unsigned char prcgCfg=0x13;// 1,3 -22% on current 3.1 -> 2.4uA/pix
+ #endif //POWER_SAVE
+
cmd(0xfd); cmd(0x12); // Disable command lock
cmd(0xae); // Display OFF
- cmd(0xd5); cmd(0xa0); // Oscillator 0xa no divider
+ cmd(0xd5); cmd(oscCfg); // Oscillator
cmd(0xa8); cmd(height-1); // Number of rows 64
cmd(0xd3); cmd(0x00); // Display offset 0
cmd(0x40); // Display start line 0
@@ -141,7 +168,7 @@ DisplayErOledm024::DisplayErOledm024() : DisplayGeneric1BPP(128,64)
cmd(0xc8); // Scan direction 64 to 1
cmd(0xda); cmd(0x12); // Alternate COM, no COM left/right
cmd(0x81); cmd(0x32); // Brightness 1.1uA/pixel
- cmd(0xd9); cmd(0x25); // Precharge phase2=2 phase1=5
+ cmd(0xd9); cmd(prcgCfg); // Precharge phase2=2 phase1=5
cmd(0xdb); cmd(0x34); // VCOMH=.78*VCC
cmd(0xa6); // Normal display mode
cmd(0xa4); // Disable test mode
--
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