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The mcp9808 test code seems not to exist anymore.

Function "float readTempF( void )" declared in Adafruit_MCP9808.h but not defined in Adafruit_MCP9808.cpp.

Longer delay in Adafruit_MCP9808::wake() for for highest resolution mode / slowest temperature conversion time needed?

I have the following setup:

Adafruit_MCP9808 mcp_internal = Adafruit_MCP9808();
void setup() {
  if (!mcp_internal.begin(0x19)) {
    Serial.println("Couldn't find MCP9808! Check your connections and verify the address is correct.");
  }
  mcp_internal.setResolution(3);
}

void loop() {
  mcp_internal.wake();
  float c = mcp_internal.readTempC();
  mcp_internal.shutdown(); 
  Serial.print(c, 4); Serial.println("*C");
}

Tried on Seeduino 4.2 and DIY-Arduino (8 MHz internal clock).

With delay(250) I get the same reading every time:

27.6250*C
27.6250*C
27.6250*C
...

Increasing the delay to values greater than 250 and I am seeing all measurements as expected.
The datasheet only states a Typical conversion time of 250 ms for the highest resolution, so this might not be enough in my case.

Not using the wake() function and calling shutdown_wake(false) + delay of course works, though a first-time user might be surprised.

I don't think calling _wire->begin(); in ::init() is a good idea in PR #21 . Lets say on ESP8266 you can remap I2C pins and specify different speed so you init the I2C object outside this class and you pass on as reference.

Adafruit_MCP9808 mcp;

void setup() {
    Wire.begin(SDA_2, SCL_2);
    Wire.setClock(400000);

    mcp.begin(&Wire);
}

I think that _wire->begin() should be only in ::begin() and ::begin(uint8_t addr)

If the device is not in shutdown mode and shutdown_wake(0) is done, the function sets the shutdown bit to a 1 which puts the chip in shutdown mode. In other words, it has the opposite effect.

  tempsensor.shutdown_wake(0);

int Adafruit_MCP9808::shutdown_wake( uint8_t sw_ID )

    if (sw_ID == 0)
     {
-       conf_shutdown = conf_register ^ MCP9808_REG_CONFIG_SHUTDOWN ;
+       conf_shutdown = conf_register & ~MCP9808_REG_CONFIG_SHUTDOWN ;

The current code toggles the shutdown bit using XOR instead of zeroing the bit.