MC56F8257MLH Freescale Semiconductor, MC56F8257MLH Datasheet - Page 470

• Manufacturer Part Number: MC56F8257MLH
• Description: DSC 64K FLASH 60MHZ 64-LQFP
• Manufacturer: Freescale Semiconductor
• Series: 56F8xxxr

Specifications of MC56F8257MLH

• Core Processor: 56800E
• Core Size: 16-Bit
• Speed: 60MHz
• Connectivity: CAN, I²C, LIN, SCI, SPI
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Ram Size: 4K x 16
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 16x12b, D/A 1x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 64-LQFP
• Product: DSCs
• Processor Series: 56800E
• Core: 56800E
• Device Million Instructions Per Second: 60 MIPs
• Maximum Clock Frequency: 60 MHz
• Number Of Programmable I/os: 54
• Data Ram Size: 8 KB
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit, 8 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

Functional Description
The clock source bit (CLKSRC) in the CAN_CTL1 register defines whether the internal
CAN_CLK is connected to the output of a crystal oscillator (oscillator clock) or to the
bus clock.
The clock source must be chosen such that the tight oscillator tolerance requirements (up
to 0.4%) of the CAN protocol are met. Additionally, for high CAN bus rates (1 Mbps), a
45% to 55% duty cycle of the clock is required.
If the bus clock is generated from a PLL, select the oscillator clock rather than the bus
clock because of jitter considerations, especially at the faster CAN bus rates.
A programmable prescaler generates the time quanta (Tq) clock from CAN_CLK. A time
quantum is the atomic unit of time handled by the MSCAN.
f
A bit time is subdivided into three segments as described in the Bosch CAN
specification.
Bit Rate = f
470
Tq
• SYNC_SEG: This segment has a fixed length of one time quantum. Signal edges are
• Time Segment 1: This segment includes the PROP_SEG and the PHASE_SEG1 of
• Time Segment 2: This segment represents the PHASE_SEG2 of the CAN standard. It
= f
expected to happen within this section.
the CAN standard. It can be programmed by setting the parameter TSEG1 to consist
of 4 to 16 time quanta.
can be programmed by setting the TSEG2 parameter to be 2 to 8 time quanta long.
CANCLK
O s c illa to r C lo c k
B u s C lo c k
/ (Prescaler value)
Tq
/ (number of Time Quanta)
MC56F825x/4x Reference Manual, Rev. 2, 10/2010
Figure 13-85. MSCAN Clocking Scheme
C L K S R C
Preliminary
C A N C L K
M S C A N
C L K S R C
P r e s c a le r
(1 .. 6 4 )
T im e q u a n ta c lo c k (T q )
Freescale Semiconductor