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S6E1A1 DMA Timeout BT UART | 赛普拉斯半导体

S6E1A1 DMA Timeout BT UART

2016 年 6 月 17 日

MFS0 is initialized to UART mode, 8N1 and 115.2 kBits/s.
BT0 is initialized to one-shot mode, retriggerable and count time of 1 s.
Some strings are output and finally each received character is stored in a buffer via UART0-RX-DMA (ch.1). If there is no reception for more than 1 s, the BT0 counter underflows and its interrupt service routine is called for notification that there was a time-out caused of a reception bus idle state.
The BT0 is retriggerd via DMA (ch. 0), writing the retrigger value to TMCR at each UART4 RX IRQ demand.
Note that the UART's DMA must have a lower DMA priority than the timer DMA, because it clears the request flag after reading the RDR via DMA. The DMA for the timer would be cleared during that otherwise.

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