[eps]

In the example, shouldn't it be checking that stop bits are ones?

Does available() extract and discard the bit if one's available? Or does it act a flag that's reset upon reading? Why doesn't loop() extract stop bits then?

I mean, this is clearly aimed at a technical audience with embedded background, so the code should really match the specs, even if it's just an illustartive example :)

[MootWoop]

Hi I'm the person who wrote this example. In fact you don't need to check that stop bits are ones because one is the default: when nothing is being written on the line, it is high all the time. This is why it's just a matter of convention (number of stop bits) rather than a specific pattern.

EDIT: available checks that data is available on a port. If the test is true, then you can read from the port; if you don't read from the port, this is equivalent to an implicit read and data is discarded.

[kw71]

Hi. I think this UART can be made better. A typical hardware UART receiver is clocked at a multiple of the signalling rate (16x is common) and the pin is sampled according to the clock. During the middle of the bit period, marks on the bus affect a counter whose value is compared to a constant, the result of which indicates whether the majority of samples indicate a mark or a space. The result of this goes into the receive shift register. The samples from the beginning and the end of the bit period are discarded.

This mechanism allows for timing differences between either end, and some immunity to electrical noise.

Also, sampling and validating the stop bit(s) will reveal framing errors.

[MootWoop]

Thank you for your insight and suggestions! This example is really a toy implementation to show what the Cx language looks like, so it is not really suited for a robust hardware core. With this example I put the emphasis on how easy it is to understand what the Cx code does, and UART is a good use case because it is small enough.