S912XEG128J2VAL
| Model | S912XEG128J2VAL |
| Description | IC,MICROCONTROLLER,16-BIT,CPU12 CPU,CMOS,QFP,112PIN,PLASTIC |
| PDF file | Total 1327 pages (File size: 7M) |
| Chip Manufacturer | ROCHESTER |
Chapter 20 Serial Communication Interface (S12SCIV5)
20.5.2.2
Wait Mode
Because of an order from the United States International Trade Commission, BGA-packaged product lines and part numbers indicated here currently are not
available from Freescale for import or sale in the United States prior to September 2010: S12XE products in 208 MAPBGA packages
SCI operation in wait mode depends on the state of the SCISWAI bit in the SCI control register 1
(SCICR1).
• If SCISWAI is clear, the SCI operates normally when the CPU is in wait mode.
• If SCISWAI is set, SCI clock generation ceases and the SCI module enters a power-conservation
state when the CPU is in wait mode. Setting SCISWAI does not affect the state of the receiver
enable bit, RE, or the transmitter enable bit, TE.
If SCISWAI is set, any transmission or reception in progress stops at wait mode entry. The
transmission or reception resumes when either an internal or external interrupt brings the CPU out
of wait mode. Exiting wait mode by reset aborts any transmission or reception in progress and
resets the SCI.
20.5.2.3
Stop Mode
The SCI is inactive during stop mode for reduced power consumption. The STOP instruction does not
affect the SCI register states, but the SCI bus clock will be disabled. The SCI operation resumes from
where it left off after an external interrupt brings the CPU out of stop mode. Exiting stop mode by reset
aborts any transmission or reception in progress and resets the SCI.
The receive input active edge detect circuit is still active in stop mode. An active edge on the receive input
can be used to bring the CPU out of stop mode.
20.5.3
Interrupt Operation
This section describes the interrupt originated by the SCI block.The MCU must service the interrupt
requests.
Table 20-20
lists the eight interrupt sources of the SCI.
Table 20-20. SCI Interrupt Sources
Interrupt
TDRE
TC
RDRF
OR
IDLE
Source
SCISR1[7]
SCISR1[6]
SCISR1[5]
SCISR1[3]
SCISR1[4]
ILIE
RXEDGIE
BERRIE
BRKDIE
Local Enable
TIE
TCIE
RIE
Description
Active high level. Indicates that a byte was transferred from SCIDRH/L to the
transmit shift register.
Active high level. Indicates that a transmit is complete.
Active high level. The RDRF interrupt indicates that received data is available
in the SCI data register.
Active high level. This interrupt indicates that an overrun condition has occurred.
Active high level. Indicates that receiver input has become idle.
Active high level. Indicates that an active edge (falling for RXPOL = 0, rising for
RXPOL = 1) was detected.
Active high level. Indicates that a mismatch between transmitted and received data
in a single wire application has happened.
Active high level. Indicates that a break character has been received.
RXEDGIF SCIASR1[7]
BERRIF
BKDIF
SCIASR1[1]
SCIASR1[0]
20.5.3.1
Description of Interrupt Operation
The SCI only originates interrupt requests. The following is a description of how the SCI makes a request
and how the MCU should acknowledge that request. The interrupt vector offset and interrupt number are
MC9S12XE-Family Reference Manual Rev. 1.19
Freescale Semiconductor
757
