MCF5272CVF66J Freescale Semiconductor, MCF5272CVF66J Datasheet - Page 381

• Manufacturer Part Number: MCF5272CVF66J
• Description: IC MCU 166MHZ 196MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: MCF527xr

Specifications of MCF5272CVF66J

• Core Processor: Coldfire V2
• Core Size: 32-Bit
• Speed: 66MHz
• Connectivity: EBI/EMI, Ethernet, I²C, SPI, UART/USART, USB
• Peripherals: DMA, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (4K x 32)
• Program Memory Type: ROM
• Ram Size: 1K x 32
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 196-MAPBGA
• Processor Series: MCF527x
• Core: ColdFire V2
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: NNDK-MOD5272-KIT, NNDK-MOD5270-KIT
• Leaded Process Compatible: No
• Rohs Compliant: No
• Peak Reflow Compatible (260 C): No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: No

to improve the accuracy of the clock source as shown in the following example using a 48 MHz CLKIN
and 230kbs UART baud rate:
16.5.1.2.2
An external source clock (URT_CLK) can be used as is or divided by 16.
16.5.1.2.3
The UART can determine the clock rate of a received character stream from the timing of the received
pattern. If UCRn[ENAB] is set, the autobaud detector searches for a low level on URT_RxD, indicating a
start bit. Start-bit length is measured until URT_RxD returns to a high level, then the transmission rate is
calculated and loaded into UDUn, UDLn, and UFPDn.
The calculated transmission rate can be determined by reading UABUn and UABLn. Errors may occur in
the calculation of high transmission rates due to distortion effects from the external drivers. If the
calculated rate is inaccurate, UDUn, UDLn, and UFPDn must be written with the appropriate value as soon
as possible to ensure that characters are properly received by the UART. The first character is always
correctly captured, even though the transmission rate is not yet calculated.
The first character must be an odd character such as ‘a’ or ‘A’ to ensure that it contains an isolated start
bit. The parity mode can be determined by monitoring subsequent characters.
The process for using the autobaud detector is as follows:
Freescale Semiconductor
1. UART Divider= CLKIN / (16 x 2 x UART Baud Rate)
2. The truncation has resulted in an effective 8.7% error (0.52/6)
3. Using the formula Fractional Divider = (truncated remainder * 16)
4. This now gives an effective total error in the baud rate as:
•
•
•
•
UDUn, UDLn, and UFPDn must be initialized to 0x00.
The receiver and transmitter clock sources must be set to TIMER (UCSR = 0xDD).
Autobaud must be enabled (UCR[ENAB] = 1).
The receiver must be enabled (UCR[RC] = 01).
%Error = 100 x (Truncated remainder) / (16 x (UD + UFPD/16)]
External Clock
Autobaud Detection
MCF5272 ColdFire
= 48E06 / (32 x 230E03)
= 6.52
= 6 (truncate to lowest whole number)
UDU = 0x00, UDL = 0x06
= 0.52 * 16
= 8.32
= 8 (truncate to nearest whole number)
UFPD = 0x08
= 100 x 0.32 / (16 x (6 + 8/16))
= 32 / 104
= 0.31%
Baudrate
®
Integrated Microprocessor User’s Manual, Rev. 3
=
Externalclockfrequency
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16or1
UART Modules
16-21