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Serial Communication Controllers (SCCs)
MC68360 USER’S MANUAL
However, the R-bit will be cleared if an error occurs during transmission, regard-
less of the CM bit.
BR—BCS Reset
0 = The transmitter BCS accumulation is not reset.
1 = The transmitter BCS accumulation is reset (used for STX or SOH) before sending
the data buffer.
TD—Transmit DLE
0 = No automatic DLE transmission is to occur before the data buffer.
1 = The transmitter will transmit a DLE character before sending the data buffer, which
saves writing the first DLE to a separate data buffer when working in transparent
mode. See the TR bit for information on control characters.
TR—Transparent Mode
0 = The transmitter will enter (remain in) the normal mode after sending the data buffer.
In this mode, the transmitter will automatically insert SYNCs in an underrun condi-
tion.
1 = The transmitter enters or remains in transparent mode after sending the data buff-
er. In this mode, the transmitter automatically inserts DLE-SYNC pairs in the un-
derrun condition. Underrun occurs when the BISYNC controller finishes a buffer
with the L-bit set to zero and the next BD is not available. The transmitter also
checks all characters before sending them; if a DLE is detected, another DLE is
automatically sent. The user must insert a DLE or program the BISYNC controller
to insert it (using TD) before each control character required. The transmitter will
calculate the CRC16 BCS even if the BCS bit in the BISYNC mode register is pro-
grammed to LRC. The PTCRC should be initialized to CRC16 before setting this
bit.
B—BCS Enable
0 = Buffer consists of characters to be excluded from the BCS accumulation.
1 = Buffer consists of characters to be included in the BCS accumulation.
The following status bits are written by the CP after it has finished transmitting the associ-
ated data buffer.
UN—Underrun
The BISYNC controller encountered a transmitter underrun condition while transmitting
the associated data buffer.
CT—CTS Lost
CTS was lost during message transmission.
Data Length
The data length is the number of octets that the CP should transmit from this BD’s data
buffer. It is never modified by the CP. The data length should be greater than zero.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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