mc68hc08ln56 Freescale Semiconductor, Inc, mc68hc08ln56 Datasheet - Page 148

• Manufacturer Part Number: mc68hc08ln56
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Communications Interface Module (SCI)
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in
the count of the transmitting device is 10 bit times × 16 RT cycles = 160 RT cycles.
The maximum per cent difference between the receiver count and the transmitter count of a fast 8-bit
character with no errors is
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
With the misaligned character shown in
the count of the transmitting device is 11 bit times × 16 RT cycles = 176 RT cycles.
The maximum per cent difference between the receiver count and the transmitter count of a fast 9-bit
character with no errors is
12.4.3.6 Receiver Wake-Up
So that the MCU can ignore transmissions intended only for other receivers in multiple-receiver systems,
the receiver can be put into a standby state. Setting the receiver wake-up bit, RWU, in SCC2 puts the
receiver into a standby state during which receiver interrupts are disabled.
Depending on the state of the WAKE bit in SCC1, either of two conditions on the PTE6/RxD pin can bring
the receiver out of the standby state:
148
•
•
Address mark — An address mark is a logic one in the most significant bit position of a received
character. When the WAKE bit is set, an address mark wakes the receiver from the standby state
by clearing the RWU bit. The address mark also sets the SCI receiver full bit, SCRF. Software can
then compare the character containing the address mark to the user-defined address of the
receiver. If they are the same, the receiver remains awake and processes the characters that
follow. If they are not the same, software can set the RWU bit and put the receiver back into the
standby state.
Idle input line condition — When the WAKE bit is clear, an idle character on the PTE6/RxD pin
wakes the receiver from the standby state by clearing the RWU bit. The idle character that wakes
the receiver does not set the receiver idle bit, IDLE, or the SCI receiver full bit, SCRF. The idle line
type bit, ILTY, determines whether the receiver begins counting logic ones as idle character bits
after the start bit or after the stop bit.
With the WAKE bit clear, setting the RWU bit after the RxD pin has been
idle may cause the receiver to wake up immediately.
MC68HC08LN56 • MC68HC708LN56 General Release Specification, Rev. 2.1
154 160
----------------------- -
170 176
----------------------- -
Figure
Figure
154
170
–
–
12-10, the receiver counts 154 RT cycles at the point when
12-10, the receiver counts 170 RT cycles at the point when
NOTE
×
×
100
100
=
=
3.90%
3.53%
·
Freescale Semiconductor