Hang if no pull-up present

[xross]

The lib includes a wait on SCL high, this is either an event or a polling loop, dependent on implementation.

If this is called on a system where the pull up isn't present then the project can hang forever - not ideal.

If would be better if this error was detected and reported to the developer.

This could be done with timeouts or a simple check for pull-up present at init time.

Real world use case is running USB Audio project on a custom board - we ideally don't want it to hang.

[XMOS-JoeG]

Example:

lib_i2c/lib_i2c/src/i2c_master.xc

Line 58 in 648351b

p_scl when pinseq(1) :> void;

in release_clock_and_wait function. Yes function should wait until clock goes high, but not forever!

Should timeout and report error or similar.

[xross]

Polling loop example:

lib_i2c/lib_i2c/src/i2c_master_single_port.xc

Line 69 in 82e82f2

while (!(val & SCL_HIGH)) {