MC68HC908AP16CFB datasheet(228/440 Pages) MOTOROLA

228 / 440 page

Serial Communications Interface

Data Sheet

MC68HC908AP Family — Rev. 2.5

228

MOTOROLA

The maximum percent difference between the receiver count and the

transmitter count of a fast 9-bit character with no errors is

13.4.3.6 Receiver Wakeup

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 wakeup 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 RxD pin can bring the receiver out of the standby state:

•

Address mark — An address mark is a logic 1 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 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 1s as idle character bits after the

start bit or after the stop bit.

NOTE:

With the WAKE bit clear, setting the RWU bit after the RxD pin has been

idle may cause the receiver to wake up immediately.

170

176

–

170

--------------------------

100

3.53%

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

MC68HC908AP16CFB Datasheet(PDF) 228 Page - Motorola, Inc

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