MC9S12E128CPV Freescale Semiconductor, MC9S12E128CPV Datasheet - Page 271

• Manufacturer Part Number: MC9S12E128CPV
• Description: Microcontrollers (MCU) 16 Bit 16MHz
• Manufacturer: Freescale Semiconductor

Specifications of MC9S12E128CPV

• Data Bus Width: 16 bit
• Program Memory Type: Flash
• Program Memory Size: 128 KB
• Data Ram Size: 8 KB
• Interface Type: SCI, SPI
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 92
• Number Of Timers: 16 bit
• Operating Supply Voltage: 3.135 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: LQFP-112
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• On-chip Dac: 8 bit, 2 Channel
• Lead Free Status / Rohs Status: No RoHS Version Available

8.4.5.5
A transmitting device may be operating at a baud rate below or above the receiver baud rate. Accumulated
bit time misalignment can cause one of the three stop bit data samples (RT8, RT9, and RT10) to fall
outside the actual stop bit. A noise error will occur if the RT8, RT9, and RT10 samples are not all the same
logical values. A framing error will occur if the receiver clock is misaligned in such a way that the majority
of the RT8, RT9, and RT10 stop bit samples are a logic 0.
As the receiver samples an incoming frame, it re-synchronizes the RT clock on any valid falling edge
within the frame. Re synchronization within frames will correct a misalignment between transmitter bit
times and receiver bit times.
8.4.5.5.1
Figure 8-22
framing error. The slow stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit data
samples at RT8, RT9, and RT10.
Let’s take RTr as receiver RT clock and RTt as transmitter RT clock.
For an 8-bit data character, it takes the receiver 9 bit times x 16 RTr cycles +7 RTr cycles =151 RTr cycles
to start data sampling of the stop bit.
With the misaligned character shown in
the count of the transmitting device is 9 bit times x 16 RTt cycles = 144 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a slow 8-bit data
character with no errors is:
For a 9-bit data character, it takes the receiver 10 bit times x 16 RTr cycles + 7 RTr cycles = 167 RTr cycles
to start data sampling of the stop bit.
With the misaligned character shown in
the count of the transmitting device is 10 bit times x 16 RTt cycles = 160 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a slow 9-bit
character with no errors is:
Freescale Semiconductor
((151 – 144) / 151) x 100 = 4.63%
((167 – 160) / 167) X 100 = 4.19%
shows how much a slow received frame can be misaligned without causing a noise error or a
Baud Rate Tolerance
Slow Data Tolerance
RECEIVER
RT CLOCK
MC9S12E128 Data Sheet, Rev. 1.07
MSB
Figure
Figure
Figure 8-22. Slow Data
8-22, the receiver counts 151 RTr cycles at the point when
8-22, the receiver counts 167 RTr cycles at the point when
SAMPLES
DATA
Chapter 8 Serial Communication Interface (SCIV3)
STOP
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