Question

1. Fill in the blanks to configure the SCII module of HCS12 with the following settings 14400 baud (Bus clock is 24 MHz) SCI enabled in wait mode One start bit, 8 data bits, one stop bit Enable transmit and receive Enable TDRE (TX data register empty) interrupt Enable RDRF (RX data register full) interrupt No loop back Enablc parity checking and use odd parity ; ; 14400 baud SCI enabled in wait mode; enable parity and use odd parity SCI1BD - SCI1CR1- SCI1CR2I/ Enable TDRE and RDRF interrupts; enable TX and RX 2. Fill in the blanks to configure the HCS12 SPI module to operate with the following settings Baud rate set to 500 KHz (Bus clock is 24 MHz) Master mode Enable TX/RX interrupts Clock pin idle high (active low) with data sampled on the rising edge of the clock . Disable slave select output Shift least significant bit first SPI clock operates normally in stop mode SPIOBR - 3. An I2C communication has been captured by a mixed signal oscilloscope. SDA is the blue waveform and SCL is the red one. The address and data portions are indicated in the picture RWI A Slave address Data a) What is the address of the slave? b) What is the data value being transferred? Is the master reading or writing the data?

Answer 1

Answer :- 1) The expression for baud rate register value is given by-

clock BR 1 16 baud rate

thus the register value is-

24000000 BR 104.166 16 14400

Taking the value as 105, in hexadecimal it is 0x069.

Hence SCI1BD = 0x069.

; To enable parity with odd parity, SCI wait mode, one start, stop and 8 data bits.
SCICR1 = 0b00000011 = 0x03.

;To enable TDRE, RDRF, TX and RX enable bit.
SCICR2 = 0b10101100 = 0xAC.

Answer :- 3)a) The the start bit, the next 7 bits are slave address. Thus from the given signal graph, we get the 7-bits as-

slave bits = 0011010 = 0x1A.

Answer :- 3)b) After the acknowledgement bit A, the next 8-bit is the data value. Thus the data value after Ack bit (A) is-

Data = 00010010 = 0x12.

The master is reading the data from slave as R/W' = 1, just after 7-bit of slave address bit.

start slave address data value Slave address RW A Data