COP8SGE5_14 Datasheet, PDF (39/82 Pages) Texas Instruments – COP8SG Family 8-Bit CMOS ROM Based and OTP Microcontrollers with 8k to 32k Memory, Two Comparators and USART

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COP8SGE5, COP8SGE7, COP8SGH5
COP8SGK5, COP8SGR5, COP8SGR7
SNOS516E – JANUARY 2000 – REVISED APRIL 2013
The third format for transmission (CHL0 = 0, CHL1 = 1) consists of one Start bit, nine Data bits and 7/8, one or
two Stop bits. This format also supports the USART “ATTENTION” feature. When operating in this format, all
eight bits of TBUF and RBUF are used for data. The ninth data bit is transmitted and received using two bits in
the ENU and ENUR registers, called XBIT9 and RBIT9. RBIT9 is a read only bit. Parity is not generated or
verified in this mode.
For any of the above framing formats, the last Stop bit can be programmed to be 7/8th of a bit in length. If two
Stop bits are selected and the 7/8th bit is set (selected), the second Stop bit will be 7/8th of a bit in length.
The parity is enabled/disabled by PEN bit located in the ENU register. Parity is selected for 7- and 8-bit modes
only. If parity is enabled (PEN = 1), the parity selection is then performed by PSEL0 and PSEL1 bits located in
the ENU register.
Note that the XBIT9/PSEL0 bit located in the ENU register serves two mutually exclusive functions. This bit
programs the ninth bit for transmission when the USART is operating with nine data bits per frame. There is no
parity selection in this framing format. For other framing formats XBIT9 is not needed and the bit is PSEL0 used
in conjunction with PSEL1 to select parity.
The frame formats for the receiver differ from the transmitter in the number of Stop bits required. The receiver
only requires one Stop bit in a frame, regardless of the setting of the Stop bit selection bits in the control register.
Note that an implicit assumption is made for full duplex USART operation that the framing formats are the same
for the transmitter and receiver.
Figure 31. Framing Formats
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