Modify transfer16 API

[s1498n089]

Modify return value of transfer16 function.

[S10143806H]

Dear @s1498n089,
Thank you for your Pull Request. We have tested and verified your PR.
Would you like to modify your code as: _data = t.val;
instead of using _data = t.msb << 8 | t.lsb;?

The reason for the above suggestion is due to both val, msb, and lsb are included in the same union structure as shown in the code below:
https://github.com/ambiot/ambd_arduino/blob/6bbf7b9075e94a3b0bc7fa26dcee920d7daf23e4/Arduino_package/hardware/libraries/SPI/SPI.cpp#L244
To know more about the union structure, please refer to this link.

Thank you again.

[M-ichae-l]

I believe both function transfer and transfer16 return "0" for successful transfer instead of the value. So "0" is the correct return otherwise the transfer process is failed.

[s1498n089]

Dear @s1498n089, Thank you for your Pull Request. We have tested and verified your PR. Would you like to modify your code as: _data = t.val; instead of using _data = t.msb << 8 | t.lsb;?

The reason for the above suggestion is due to both val, msb, and lsb are included in the same union structure as shown in the code below:

https://github.com/ambiot/ambd_arduino/blob/6bbf7b9075e94a3b0bc7fa26dcee920d7daf23e4/Arduino_package/hardware/libraries/SPI/SPI.cpp#L244

To know more about the union structure, please refer to this link.
Thank you again.

Dear @S10143806H
Okay, I'll modifying the code to use union. I didn't notice it was union at the time, as I instinctively used the | operator. Thank you for the suggestion!