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This program have three I/O functions that connect to UART driver via ioctl : (read(), write() and select()), but only select() and write() and put program in change process stat to sleep modeuntil system don't receive or transmit information via UART, the proceess process awake when I/O task is completed. Select functions "select" function is used to prevent that readswas reads can blocked when there aren't data avaliable.The next captures are do it with GPIO debug mode and 300 bauds speed. Blue=UART1, Violet=write function time and Green=select function time.<br>
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