MLX90614 support

[jdavid]

In v032 to support MLX90614 it was enough to add the sendStop parameter to the endTransmission and requestFrom functions, as it's done in Arduino. See https://www.libelium.com/forum/viewtopic.php?f=27&t=13616&start=10#p56594

However since v033 the twi and Wire/I2C code has changed very much, the endTransmission and requestFrom functions don't exist anymore, and MLX90614 doesn't work.

How to implement this feature with the new code?

[jdavid]

After further testing, actually it works fine except for scanning, I2C.scan(0x5A) returns an error.

Scanning with the old Wire library would be implemented like this:

Wire.beginTransmission(0x5A);
error = Wire.endTransmission();

And it works correctly.

[jdavid]

I've fixed it with this change:

diff --git a/waspmote-api/WaspI2C.cpp b/waspmote-api/WaspI2C.cpp
index 87949f7..a972926 100644
--- a/waspmote-api/WaspI2C.cpp
+++ b/waspmote-api/WaspI2C.cpp
@@ -330,11 +330,11 @@ uint8_t WaspI2C::scan(uint8_t devAddr)
        packet_received.addr_length  = TWI_SLAVE_NO_INTERNAL_ADDRESS;   /* TWI slave memory address data size */
        packet_received.chip         = (devAddr << 1);          /* TWI slave bus address */
        packet_received.buffer       = buffer;  /* transfer data destination buffer */
-       packet_received.length       = 1;               /* transfer data size (bytes) */
+       packet_received.length       = 0;               /* transfer data size (bytes) */
 
        /* Perform a multi-byte read access then check the result. */
        I2C.secureBegin();
-       error = twi_master_read(&TWBR,&packet_received);
+       error = twi_master_write(&TWBR,&packet_received);
        
        return error;

[jdavid]

By the way, why there're 2 calls to RTC.ON() here?
https://github.com/Libelium/waspmoteapi/blob/master/waspmote-api/main.cpp#L77