mc68hc908jb16 Freescale Semiconductor, Inc, mc68hc908jb16 Datasheet - Page 216

• Manufacturer Part Number: mc68hc908jb16
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Communications Interface
12.5.2.3 Break Characters
12.5.2.4 Idle Characters
Technical Data
216
Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit
shift register with a break character. A break character contains all logic
0s and has no start, stop, or parity bit. Break character length depends
on the M bit in SCC1. As long as SBK is at logic 1, transmitter logic
continuously loads break characters into the transmit shift register. After
software clears the SBK bit, the shift register finishes transmitting the
last break character and then transmits at least one logic 1. The
automatic logic 1 at the end of a break character guarantees the
recognition of the start bit of the next character.
The SCI recognizes a break character when a start bit is followed by
eight or nine logic 0 data bits and a logic 0 where the stop bit should be.
Receiving a break character has these effects on SCI registers:
An idle character contains all logic 1s and has no start, stop, or parity bit.
Idle character length depends on the M bit in SCC1. The preamble is a
synchronizing idle character that begins every transmission.
If the TE bit is cleared during a transmission, the TxD pin becomes idle
after completion of the transmission in progress. Clearing and then
setting the TE bit during a transmission queues an idle character to be
sent after the character currently being transmitted.
•
•
•
•
•
•
Serial Communications Interface Module (SCI)
Sets the framing error bit (FE) in SCS1
Sets the SCI receiver full bit (SCRF) in SCS1
Clears the SCI data register (SCDR)
Clears the R8 bit in SCC3
Sets the break flag bit (BKF) in SCS2
May set the overrun (OR), noise flag (NF), parity error (PE), or
reception in progress flag (RPF) bits
MC68HC908JB16
Freescale Semiconductor
—
Rev. 1.1