FreeRTOS+IO V1.0.1 with FreeRTOS V7.5.2
I encountered a case where writes were timing out unexpectedly. It turned out to be a bug in the ioutilsBLOCKING_SEND_CHARS_TO_TX_QUEUE macro. Here is what I think was happening:
A previous transmission was in progress, about to finish.
The write got to the xQueueSend call and added a byte to the queue.
The ISR fired and emptied the queue.
The write then gets to the xQueueReceive call, which waits until timeout for something to be placed in the queue.
The attached patch changes the timeout to 0 so that more can be placed in the queue when it is empty.
Being replaced by the 'common IO' interface.