MC812A4CPVE8 Freescale Semiconductor, MC812A4CPVE8 Datasheet - Page 156

• Manufacturer Part Number: MC812A4CPVE8
• Description: IC MCU 16BIT EEPROM 4K 112-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC12r

Specifications of MC812A4CPVE8

• Core Processor: CPU12
• Core Size: 16-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: POR, WDT
• Number Of I /o: 83
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: EEPROM
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 112-LQFP
• Processor Series: HC812A
• Core: HC12
• Data Bus Width: 16 bit
• Data Ram Size: 1 KB
• Interface Type: SCI, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 91
• Number Of Timers: 8
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit, 8 Channel
• Controller Family/series: 68HC12
• No. Of I/o's: 91
• Eeprom Memory Size: 4KB
• Ram Memory Size: 1KB
• Cpu Speed: 8MHz
• No. Of Timers: 1
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

Serial Communications Interface Module (SCI)
14.5.2 Baud Rate Generation
A 13-bit modulus counter in the baud rate generator derives the baud rate for both the receiver and the
transmitter. The value from 0 to 8191 written to the SBR12–SBR0 bits determines the module clock
divisor. The SBR bits are in the SCI baud rate registers (SCBDH and SCBDL). The baud rate clock is
synchronized with the bus clock and drives the receiver. The baud rate clock divided by 16 drives the
transmitter. The receiver has an acquisition rate of 16 samples per bit time.
Baud rate generation is subject to two sources of error:
Table 14-3
MHz.
14.5.3 Transmitter
A block diagram of the SCI transmitter is shown in
14.5.3.1 Character Length
The SCI transmitter can accommodate either 8-bit or 9-bit data characters. The state of the M bit in SCI
control register 1 (SCCR1) determines the length of data characters. When transmitting 9-bit data, bit T8
in SCI data register high (SCDRH) is the ninth bit (bit 8).
14.5.3.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a frame out to the TXD pin. The SCI data
registers (SCDRH and SCDRL) are the write-only buffers between the internal data bus and the transmit
shift register.
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Integer division of the module clock may not give the exact target frequency.
Synchonization with the bus clock can cause phase shift.
lists some examples of achieving target baud rates with a module clock frequency of 10.2
1. The baud rate divisor is the value written to the SBR12–SBR0 bits.
2. The receiver clock frequency is the MCLK frequency divided by the baud rate divisor.
3. The transmitter clock frequency is the receiver clock frequency divided by 16.
Baud Rate
Divisor
17
33
66
133
266
531
1062
2125
4250
5795
(1)
Table 14-3. Baud Rates (Module Clock = 10.2 MHz)
Clock Rate (Hz)
600,000.0
309,090.9
154,545.5
76,691.7
38,345.9
19,209.0
9604.5
4800.0
2400.0
1760.1
Receiver
MC68HC812A4 Data Sheet, Rev. 7
(2)
Clock Rate (Hz)
Figure
Transmitter
37,500.0
19,318.2
9659.1
4793.2
2396.6
1200.6
600.3
300.0
150.0
110.0
14-4.
(3)
Baud Rate
Target
38,400
19,200
9600
4800
2400
1200
600
300
150
110
Error (%)
Freescale Semiconductor
2.3
0.62
0.62
0.14
0.14
0.11
0.05
0.00
0.00
0.00