AN2866 Freescale Semiconductor / Motorola, AN2866 Datasheet - Page 13

• Manufacturer Part Number: AN2866
• Description: Migrating from the MC68332 to the ColdFire MCF523x
• Manufacturer: Freescale Semiconductor / Motorola

2.4.1.3
Moving from the MC68332’s single SCI to the three MCF523x UARTs is a move toward more
functionality; there are very few migration issues as a result of differences between these two
asynchronous communication modules. The biggest advantage in moving from the SCI to a UART is the
ability to incorporate flow control in the communication link, thereby preventing receiver overruns. This
can be accomplished with the URTS and UCTS handshaking signals of the MCF523x’s UARTs.
Table 2
Freescale Semiconductor
Clock Source
Baud Rate Divider Range
Hardware Flow Control
Programmable Number of Data Bits
Programmable Number of Stop Bits
Programmable Parity Enable
Programmable Parity Type
Force Polarity of Parity Bit
Send Break
Indication of Break Received
Framing, Parity, and Overrun Error
Indications
Transmitter Empty, Transmission Complete,
Receiver Ready/Full Indications
Idle Line, Noise Indication
Receive FIFO
Transmit FIFO
Multidrop Mode Support
Automatic Echo Mode
Local Loop-back Mode
Remote Loop-back Mode
contrasts the features of the MC68332’s SCIs and the MCF523x’s UARTs.
SCI vs. UART
Feature
Migrating from the MC68332 to the ColdFire
Table 2. SCI and UART Feature Differences
1 shift register, 1
1 shift register, 1
13-bit Prescaler 16-bit Prescaler
shared data
shared data
register
register
f
SYS
SCI
8,9
—
—
—
—
—
—
—
√
√
√
√
√
√
√
/16
1 shift register, 3
1 shift register, 1
f
data registers
dedicated Rx
dedicated Tx
SYS
data register
5,6,7,8
UART
/32, DTIN
—
®
√
√
√
√
√
√
√
√
√
√
√
√
√
MCF523x, Rev. 1.0
Parity bit setting to indicate data or
external UART clock reference on
Baud rate = Clock source divided
DMA Timer input can be used as
MCF523x’s break signal may be
by any value in specified range
Even or odd parity
address character
variable length
the MCF523x
Comments
Device Differences
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