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When ARTS is set then RTS will be asserted every time a new character is received and cleared when the receive register has been read. Manual control of RTS can be achieved by using IRTS to change the current state of the line. IRTS = 1 toggle the RS-232 RTS line low stopping incoming transmission, IRTS = 0 toggle the line high allowing incoming transmission.
The baud rates set by BAUD 2 to BAUD 0 are as follows:
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BIT NAME Function
7 - -
6 DCD If set, DCD interrupts are enabled
5 CTS If set, CTS interrupts are enabled
4 TDRE If set, transmit data register empty interrupt enabled
3 - -
2 RDRF If set, receive data register full interrupt enabled
1 - -
0 - -
UMK register masks UIT register in order to generate UART interrupt bit in STA, logic is STA[UART] = |(UIT & UMK). UIT bits are always up to date regardless of UMK value. UAK is a write only register, it resets UIT[DCDI] and UIT[CTSI] bits.
UAK ($E6), UART interrupt acknowledge register
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