Wangjialin 8d6b782327 Modify UART driver: ... 1. Add a ring buffer for UART TX. If the buffer size is set to zero, driver will not use a buffer. But we need a task to send data from buffer to fifo. I tried directly copy data in ISR, but the code looked too long for ISR. 2. Modify the format in uart.h		2016-11-01 09:22:09 +08:00
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driver	Modify UART driver:	2016-11-01 09:22:09 +08:00