From 3cc0846d78f04a0dcff91b7b465d165dc3ad06ac Mon Sep 17 00:00:00 2001
From: Rob Tillaart <rob.tillaart@gmail.com>
Date: Mon, 8 Aug 2022 21:17:42 +0200
Subject: [PATCH 1/3] Fix #105 - make setspeed more robust

- prevent out of range I2C speeds for AVR
---
 Adafruit_I2CDevice.cpp | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/Adafruit_I2CDevice.cpp b/Adafruit_I2CDevice.cpp
index 70f45b3..15c5149 100644
--- a/Adafruit_I2CDevice.cpp
+++ b/Adafruit_I2CDevice.cpp
@@ -264,33 +264,43 @@ bool Adafruit_I2CDevice::setSpeed(uint32_t desiredclk) {
 #if defined(__AVR_ATmega328__) ||                                              \
     defined(__AVR_ATmega328P__) // fix arduino core set clock
   // calculate TWBR correctly
-  uint8_t prescaler = 1;
+
+  if ((F_CPU / 18) < desiredclk) {
+    #ifdef DEBUG_SERIAL
+    Serial.println(F("I2C.setSpeed too high."));
+    #endif
+    return false;
+  }
   uint32_t atwbr = ((F_CPU / desiredclk) - 16) / 2;
+  if (atwbr > 16320) {
+    #ifdef DEBUG_SERIAL
+    Serial.println(F("I2C.setSpeed too low."));
+    #endif
+    return false;
+  }
+  
   if (atwbr <= 255) {
-    prescaler = 1;
+    atwbr /= 1;
     TWSR = 0x0;
   } else if (atwbr <= 1020) {
     atwbr /= 4;
-    prescaler = 4;
     TWSR = 0x1;
   } else if (atwbr <= 4080) {
     atwbr /= 16;
-    prescaler = 16;
     TWSR = 0x2;
-  } else if (atwbr <= 16320) {
+  } else {           //  if (atwbr <= 16320)
     atwbr /= 64;
-    prescaler = 64;
     TWSR = 0x3;
   }
+  TWBR = atwb;
+
 #ifdef DEBUG_SERIAL
   Serial.print(F("TWSR prescaler = "));
-  Serial.println(prescaler);
+  Serial.println(pow(4, TWSR));
   Serial.print(F("TWBR = "));
   Serial.println(atwbr);
 #endif
-  TWBR = atwbr;
   return true;
-
 #elif (ARDUINO >= 157) && !defined(ARDUINO_STM32_FEATHER) &&                   \
     !defined(TinyWireM_h)
   _wire->setClock(desiredclk);

From e2388229218af89c5ee5022496b335cebbf60c19 Mon Sep 17 00:00:00 2001
From: rob tillaart <rob.tillaart@gmail.com>
Date: Mon, 8 Aug 2022 21:31:17 +0200
Subject: [PATCH 2/3] clang-format

---
 Adafruit_I2CDevice.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Adafruit_I2CDevice.cpp b/Adafruit_I2CDevice.cpp
index 15c5149..5ec8c7e 100644
--- a/Adafruit_I2CDevice.cpp
+++ b/Adafruit_I2CDevice.cpp
@@ -266,19 +266,19 @@ bool Adafruit_I2CDevice::setSpeed(uint32_t desiredclk) {
   // calculate TWBR correctly
 
   if ((F_CPU / 18) < desiredclk) {
-    #ifdef DEBUG_SERIAL
+#ifdef DEBUG_SERIAL
     Serial.println(F("I2C.setSpeed too high."));
-    #endif
+#endif
     return false;
   }
   uint32_t atwbr = ((F_CPU / desiredclk) - 16) / 2;
   if (atwbr > 16320) {
-    #ifdef DEBUG_SERIAL
+#ifdef DEBUG_SERIAL
     Serial.println(F("I2C.setSpeed too low."));
-    #endif
+#endif
     return false;
   }
-  
+
   if (atwbr <= 255) {
     atwbr /= 1;
     TWSR = 0x0;
@@ -288,7 +288,7 @@ bool Adafruit_I2CDevice::setSpeed(uint32_t desiredclk) {
   } else if (atwbr <= 4080) {
     atwbr /= 16;
     TWSR = 0x2;
-  } else {           //  if (atwbr <= 16320)
+  } else { //  if (atwbr <= 16320)
     atwbr /= 64;
     TWSR = 0x3;
   }

From 319d44c093127d79ab59f585e33a5a0e1224f0ef Mon Sep 17 00:00:00 2001
From: rob tillaart <rob.tillaart@gmail.com>
Date: Mon, 8 Aug 2022 22:02:39 +0200
Subject: [PATCH 3/3] fix build

---
 Adafruit_I2CDevice.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Adafruit_I2CDevice.cpp b/Adafruit_I2CDevice.cpp
index 5ec8c7e..9b518b4 100644
--- a/Adafruit_I2CDevice.cpp
+++ b/Adafruit_I2CDevice.cpp
@@ -292,7 +292,7 @@ bool Adafruit_I2CDevice::setSpeed(uint32_t desiredclk) {
     atwbr /= 64;
     TWSR = 0x3;
   }
-  TWBR = atwb;
+  TWBR = atwbr;
 
 #ifdef DEBUG_SERIAL
   Serial.print(F("TWSR prescaler = "));