MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 444

• Manufacturer Part Number: MCF51EM256CLL
• Description: IC MCU 32BIT 256KB FLASH 100LQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF51EMr

Specifications of MCF51EM256CLL

• Core Processor: Coldfire V1
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 16x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: MCF51EM
• Core: ColdFire V1
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: RS-232, LIN
• Maximum Clock Frequency: 50 MHz
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: DEMOEM
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

16-Bit Modulo Timer (MTIM16)
MTIM16 clock select bits (CLKS1:CLKS0) in MTIMxSC are used to select the desired clock source. If
the counter is active (TSTP = 0) when a new clock source is selected, the counter continues counting from
the previous value using the new clock source.
Nine prescale values are software selectable: clock source divided by 1, 2, 4, 8, 16, 32, 64, 128, or 256.
The prescaler select bits (PS[3:0]) in MTIMxSC select the desired prescale value. If the counter is active
(TSTP = 0) when a new prescaler value is selected, the counter continues counting from the previous value
using the new prescaler value.
The MTIM16 modulo register (MTIMxMODH:L) allows the overflow compare value to be set to any
value from 0x0001 to 0xFFFF. Reset clears the modulo value to 0x0000, which results in a free running
counter.
When the counter is active (TSTP = 0), it increases at the selected rate until the count matches the modulo
value. When these values match, the counter overflows to 0x0000 and continues counting. The MTIM16
overflow flag (TOF) is set whenever the counter overflows. The flag sets on the transition from the modulo
value to 0x0000.
Clearing TOF is a two-step process. The first step is to read the MTIMxSC register while TOF is set. The
second step is to write a 0 to TOF. If another overflow occurs between the first and second steps, the
clearing process is reset and TOF stays set after the second step is performed. This will prevent the second
occurrence from being missed. TOF is also cleared when a 1 is written to TRST.
The MTIM16 allows for an optional interrupt to be generated whenever TOF is set. To enable the MTIM16
overflow interrupt, set the MTIM16 overflow interrupt enable bit (TOIE) in MTIMxSC. TOIE should
never be written to a 1 while TOF = 1. Instead, TOF should be cleared first, then the TOIE can be set to 1.
19.5.1
This section shows an example of the MTIM16 operation as the counter reaches a matching value from
the modulo register.
19-8
selected
clock source
MTIM16 clock
(PS=%0010)
MTIMxCNT
TOF
MTIMxMOD:
MTIM16 Operation Example
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
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Figure 19-8. MTIM16 Counter Overflow Example
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