Limit I2C to 400kHz on ESP32-H2. SSD1306 benchmarks for H2 and C6

denko-rb · Jul 28, 2024 · 041be66 · 041be66
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diff --git a/benchmarks/i2c_ssd1306_refresh.rb b/benchmarks/i2c_ssd1306_refresh.rb
@@ -35,6 +35,13 @@
 #   ESP32-S3            : 51.8 fps (native USB) - Changed from 64 to 128 serial ACK interval
 #   ESP32-C3            : 51.7 fps (native USB) - Changed from 64 to 128 serial ACK interval
 #
+# July 27 2024 | i7 8700k CPU | CRuby 3.3.1 | 100 frames | Average of 3 runs
+#
+#   ESP32-H2            :  7.3 fps (WCH UART bridge @ 115200, I2C @ 400kHz)
+#   ESP32-H2            : 10.9 fps (WCH UART bridge @ 230400, I2C @ 400kHz)
+#   ESP32-C6            :  8.0 fps (WCH UART bridge @ 115200, I2C @ 1MHz)
+#   ESP32-C6            : 13.2 fps (WCH UART bridge @ 230400, I2C @ 1MHz)
+#
 require 'bundler/setup'
 require 'denko'
 

diff --git a/src/lib/DenkoI2C.cpp b/src/lib/DenkoI2C.cpp
@@ -37,6 +37,14 @@ void Denko::i2cSetSpeed(uint8_t code) {
     default: Wire.setClock(100000);  break;
   }
   i2cSpeed = code;
+
+  // ESP32-H2 doesn't safely fallback if speed > 400kHz is chosen.
+  #ifdef CONFIG_IDF_TARGET_ESP32H2
+    if (i2cSpeed > 1) {
+      i2cSpeed = 1;
+      Wire.setClock(400000);
+    }
+  #endif 
 }
 
 // CMD = 33