MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 380

• 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

Timer/PWM Module(TPM)
16.4.2.4
This type of PWM output uses the up/down counting mode of the timer counter (CPWMS=1). The output
compare value in TPMCnVH:TPMCnVL determines the pulse width (duty cycle) of the PWM signal
while the period is determined by the value in TPMMODH:TPMMODL. TPMMODH:TPMMODL
should be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous
results. ELSnA will determine the polarity of the CPWM output.
If the channel-value register TPMCnVH:TPMCnVL is zero or negative (bit 15 set), the duty cycle will be
0%. If TPMCnVH:TPMCnVL is a positive value (bit 15 clear) and is greater than the (non-zero) modulus
setting, the duty cycle will be 100% because the duty cycle compare will never occur. This implies the
usable range of periods set by the modulus register is 0x0001 through 0x7FFE (0x7FFF if you do not need
to generate 100% duty cycle). This is not a significant limitation. The resulting period would be much
longer than required for normal applications.
TPMMODH:TPMMODL=0x0000 is a special case that should not be used with center-aligned PWM
mode. When CPWMS=0, this case corresponds to the counter running free from 0x0000 through 0xFFFF,
but when CPWMS=1 the counter needs a valid match to the modulus register somewhere other than at
0x0000 in order to change directions from up-counting to down-counting.
The output compare value in the TPM channel registers (times 2) determines the pulse width (duty cycle)
of the CPWM signal
CPWM output signal low and a compare occurred while counting down forces the output high. The
counter counts up until it reaches the modulo setting in TPMMODH:TPMMODL, then counts down until
it reaches zero. This sets the period equal to two times TPMMODH:TPMMODL.
Center-aligned PWM outputs typically produce less noise than edge-aligned PWMs because fewer I/O pin
transitions are lined up at the same system clock edge. This type of PWM is also required for some types
of motor drives.
Input capture, output compare, and edge-aligned PWM functions do not make sense when the counter is
operating in up/down counting mode so this implies that all active channels within a TPM must be used in
CPWM mode when CPWMS=1.
16-18
pulse width = 2 x (TPMCnVH:TPMCnVL)
period = 2 x (TPMMODH:TPMMODL); TPMMODH:TPMMODL=0x0001-0x7FFF
TPM
Center-Aligned PWM Mode
TPM
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
MODH:
CHn
COUNT=
(Figure
TPM
Figure 16-15. CPWM Period and Pulse Width (ELSnA=0)
MODL
16-15). If ELSnA=0, a compare occurred while counting up forces the
(COUNT DOWN)
COMPARE
OUTPUT
2 x
2 x
TPM
TPM
PULSE WIDTH
MODH:
COUNT= 0
CnVH:
PERIOD
TPM
TPM
MODL
CnVL
(COUNT UP)
COMPARE
OUTPUT
TPM
MODH:
COUNT=
TPM
Freescale Semiconductor
MODL