ECET 340 Week 4 HomeWork 4
1. Determine the conversion time for an ADC0804 (8-bit), where 66 clocks per bit are required, if its clock frequency is 50 kHz.
2. If an 8-bit SAR has Vref = 10 V, what is the binary value for an input voltage of 7.28 V?
3. What is the percent error for the binary answer found in Problem #2?
4. Given an 24 MHz bus speed. Write down the line(s) of instruction which set the ATD1 unit for 2MHz conversion frequency, 10-bit resolution and 8 A-to-D clocks per sample time.
5. A single 10-bit, left justified conversion of 3.75V is complete in ATD0. Assume and
i. Name the register(s) where the result of the conversion is found
ii. What are the values in each of the 16-bits of this register after conversion is complete? Assume the result is unsigned. Show work
6. Assume that a position-sensitive potentiometer can measure up to 25 cm over a voltage range of 0 to 5 V. If an 8-bit ADC outputs a value of 0111 1010, what is the distance measured?
7. Design the basic interface circuit (using an op amp) for a temperature sensor that covers a range of 0° to 70°C if the output of the sensor is 2 mV/1°C and the ADC voltage range is 0 to 4 V.
8. Design an amplifier suitable for converting the output voltage from an LM35 temperature sensor (10 mV/°C) into a signal that makes use of the full input voltage range (0-5V) of the HCS12 ADC port pins. Assume the LM35 is to measure temperatures from 0°C up to +150°C. Show work and circuit!
9. Given a sensor with W that outputs voltage in the range +1.25V to +4.25V. Show the complete interface circuitry needed to connect it to the A/D unit built-in to the HC12 Controller.
10. Write the lines of C code needed to configure the A/D converter, start the conversion, and output a hex integer in the range 0x0000 to 0xFFFF to the variable called data1 that is proportional to airflow input (0.0 to 1.0 litre/min). No further conversion is required
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