From a7230af6d748a407b0194d86c1e93e86dc06d03e Mon Sep 17 00:00:00 2001
From: Verkehrsrot <cyberman@obh.snafu.de>
Date: Sun, 13 Oct 2019 16:59:03 +0200
Subject: [PATCH] i2c scan with low speed

---
 src/i2cscan.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/i2cscan.cpp b/src/i2cscan.cpp
index c80c2af7..d6e7ff64 100644
--- a/src/i2cscan.cpp
+++ b/src/i2cscan.cpp
@@ -15,9 +15,11 @@ int i2c_scan(void) {
   // block i2c bus access
   if (I2C_MUTEX_LOCK()) {
 
+    // Scan at 100KHz low speed
+    Wire.setClock(100000);
+
     for (addr = 8; addr <= 119; addr++) {
 
-      // scan i2c bus with no more to 100KHz
       Wire.beginTransmission(addr);
       Wire.write(addr);
       i2c_ret = Wire.endTransmission();
@@ -58,6 +60,9 @@ int i2c_scan(void) {
 
     ESP_LOGI(TAG, "I2C scan done, %u devices found.", devices);
 
+    // Set back to 400KHz
+    Wire.setClock(400000);
+
     I2C_MUTEX_UNLOCK(); // release i2c bus access
   } else
     ESP_LOGE(TAG, "I2c bus busy - scan error");