MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 443

• 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

A value of 0x0000 in MTIMxMODH:L puts the MTIM16 in free-running mode. Writing to either
MTIMxMODH or MTIMxMODL latches the value into a buffer and the registers are updated with the
value of their write buffer after the second byte writing, the updated MTIMxMODH:L will take effect in
the next MITIM16 counter cycle except for the first writing of modulo after a chip reset or in BDM mode.
But after a software reset, the MTIMxMODH:L takes effect at once even if it didn’t take effect before the
reset. On the first writing of MTIMxMODH:L after chip reset, the counter is reset and the modulo takes
effect immediately. The latching mechanism may be manually reset by setting the TRST bit of MTIMxSC
register (whether BDM is active or not).
When BDM is active, the coherency mechanism is frozen such that the buffer latches remain in the state
they were in when the BDM became active, even if one or both halves of the modulo register are written
while BDM is active. Any writing to the modulo registers bypasses the buffer latches and writes directly
to the modulo register while BDM is active, and also the counter is cleared at the same time.The reading
of MTIMxMODH:L returns the modulo value which is taking effect whenever in normal run mode or in
BDM mode.
19.5
The MTIM16 is composed of a main 16-bit up-counter with 16-bit modulo register, a clock source selector,
and a prescaler block with nine selectable values. The module also contains software selectable interrupt
logic.
The MTIM16 counter (MTIMxCNTH:L) has three modes of operation: stopped, free-running, and
modulo. The counter is stopped out of reset. If the counter starts without writing a new value to the modulo
registers, it will be in free-running mode. The counter is in modulo mode when a value other than 0x0000
is in the modulo registers.
After an MCU reset, the counter stops and resets to 0x0000, and the modulo is also reseted to 0x0000. The
bus clock functions as the default clock source and the prescale value is divided by 1. To start the MTIM16
in free-running mode, write to the MTIM16 status and control register (MTIMxSC) and clear the MTIM16
stop bit (TSTP).
Four clock sources are software selectable: the internal bus clock, the fixed frequency clock (XCLK), and
an external clock on the TCLK pin, selectable as incrementing on either rising or falling edges. The
Freescale Semiconductor
MODL
Field
7:0
Reset:
Functional Description
W
R
MTIM16 Modulo (Low Byte) — These eight read/write bits contain the modulo low byte value used to reset the
counter and set TOF. Reset sets the register to 0x00.
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
7
0
Figure 19-7. MTIM16 Modulo Register Low (MTIMxMODL)
0
6
Table 19-7. MTIMxMODL Field Descriptions
0
5
0
4
Description
MODL
0
3
0
2
16-Bit Modulo Timer (MTIM16)
0
1
0
0
19-7