Fixed interrupt handler in serial_api.c for the Nordic NRF51. The last b...

[marcuschangarm]

...yte sent in a sequence would not correctly clear the interrupt flag.

[sg-]

Can you provide an example showing how this was failing?

[anpilog]

FYI:
I had similar issue with NRF51. My fix was pretty similar as well.
Unfortunately I don't remember test case for that 8(

[marcuschangarm]

The example app below crashes immediately if the fix is not applied:

http://developer.mbed.org/users/marcuschang/code/AsyncSerialTest/

[sg-]

This patch breaks other implementations of the TX irq handler such as: https://developer.mbed.org/users/sam_grove/code/BufferedSerial/

There are also a lot of FSL targets in which the TX DR irq in an empty state always fire since its 'ready' and the programmers model is to disable this when a buffer is empty. I think the API should be defined so we can write complimentary libraries in a common way or bring buffered transactions into the mbed SDK.

[marcuschangarm]

Sam, I looked at the BufferedSerial and I like your solution better, so I'm withdrawing this pull request.

Regarding the TX always firing, I get different behavior on the Nordic NRF51 depending on whether I have the Bluetooth enabled or not, i.e., interrupts only fire once without BLE.