Trouble with static buffer sizes within the RingBuffer libray

(Arduino 1.6.18.1)

- Serial communication:

If serial data are read and the attached device does not support any flow control (like most devices that you can buy) the CPU must be in receive mode all over the time. The data received are buffered in a static preallocated 128 byte buffer SAM) within the Arduino library.

The user application must periodical check if there are data and read them and must do it fast enough, before buffer overflow.

If you do for example SD-card-i/o, the SD-card may awake from sleep mode and that cost a few 100ms, you can quickly get an overflow of the serial buffer.

The only chance to overcome this situation is to align the serial buffer size to your application. If there is no flow control on receive, one cannot use a fixed size for all projects.

Please implement a simple method, that the user can set the size of the buffer from within the project (AVR, SAM, and SAMD(?)).

Currently one must modify (SAM): "Ringbuffer.h" => "#define SERIAL_BUFFER_SIZE xxxxx".

(This topic is currently in discussion within the Arduino group.)

Start with Ringbuffer.h and the SERIAL_BUFFER_SIZE definition mentioned in the issue, then compare how the Arduino library handles the buffer for AVR, SAM, and SAMD. Define how a project should set the size without editing the library, and verify that the chosen size is honored on the affected platforms.

Written by the indexing model from the issue text.