ECE 3724-«Section»
Microprocessors
Fall 2014 EXAM #4
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Unless stated otherwise, all multi-byte data values are stored in little-endian ordering.
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Use 0 for any don’t care (X) bits.
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times. I will not lie, cheat, or steal, nor will I accept the actions of those who do.
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1. (13 points) Label the following waveform, which illustrates a single character received by a
UART. Assume the format is 7 data bits, 1 stop bit, and 1 parity bit. Scantron: use D1 to D5
(A0 – E0); D6 (0A); D0 (0B); parity (0C); start (0D); stop (0E); idle (00)
hhhflllrhhhhhhhflllrhhhhhhhhhhfllllrhhhhflllllrhhhhhhhhhhhhhh
(1-2) | (3-4) | (5-6) | (7-8) | (9-10) | (11-12) | (13-14) | (15-16) | (17-18) | (19-20) | (21-22) | (23-24) | (25-26)
2. (5 points) If the value (start bit) 0101 1100 (stop bit) was received by a UART without any
errors, what is the parity? Scantron: even (A), odd (B), none (C), not enough information (D).
__________ (27)
3. (7 points) Assume a UART is configured to send 8 data bits and 1 stop bit, with no parity.
What is the maximum number of complete characters which can be transmitted in 1 ms with
a baud rate of 57,600? Scantron: use the number encoding.
__________ (28-29)
4. (10 points) The MAX517 DAC is an 8-bit I2C DAC. Give a series of I2C commands which
will set the DAC’s output to the code 0x5A. Assume pins AD3-AD1 are tied to power and
pint AD0 is tied to ground.
____________________ (30, 31, 32, 33, 34)
____________________ (35, 36, 37, 38, 39)
____________________ (40, 41, 42, 43, 44)
____________________ (45, 46, 47, 48, 49)
____________________ (50, 51, 52, 53, 54)
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5. (14 points) The ADT7420 is an I2C temperature sensor. Give a series of I2C commands to
read the contents of the temperature value most significant byte. Assume the I2C write
address is 0x90. The address of the temperature value most significant byte is 0x00. If
needed, use a restart instead of a stop followed by a start.
____________________ (55, 56, 57, 58, 59)
____________________ (60, 61, 62, 63, 64)
____________________ (65, 66, 67, 68, 69)
____________________ (70, 71, 72, 73, 74)
____________________ (75, 76, 77, 78, 79)
____________________ (80, 81, 82, 83, 84)
____________________ (85, 86, 87, 88, 89)
6. (9 points) The AD5161 is a digital potentiometer with a SPI interface. Give a series of SPI
commands which set the serial data word (which controls the resistance produced by this
device) to the value 0x89.
____________________ (90, 91, 92, 93, 94)
____________________ (95, 96, 97, 98, 99)
____________________ (100, 101, 102, 103, 104)
7. (18 points) The M95080 is an EEPROM with a SPI interface. Give a series of SPI commands
which reads the data at address 0x234.
____________________ (105, 106, 107, 108, 109)
____________________ (110, 111, 112, 113, 114)
____________________ (115, 116, 117, 118, 119)
____________________ (120, 121, 122, 123, 124)
____________________ (125, 126, 127, 128, 129)
____________________ (130, 131, 132, 133, 134)
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8.
(10 points) The LM335A is an analog temperature sensor. It outputs 2.98 V at 25 C and uses
a scale factor of 10 mV / C. Based on this information, find the slope and intercept in the
following equation. Scantron: use the number encoding.
Temperature in C = ______________ * voltage in V – ______________.
slope: d.d*10d (135-136).(137-138)*10[(139-140)]
intercept: d.d*10d (141-142).(143-144)*10[(145-146)]
9. (10 points) An ADC with N = 16, Vref = 2.7 V is used to sample the output of the LM335A.
Based on this information, find the slope in the following equation. Scantron: use the number
encoding.
Voltage in V = _______________ * code
slope: d.d*10d (147-148).(149-150)*10[(151-152)]
10. (4 points) Assume another temperature sensor produces temp in C = 300*voltage in V – 450
and another ADC obeys V = 0.034*code. Based on this information, find the slope and
intercept in the following equation. Scantron: use the number encoding.
Temperature in C = ______________ * code – ______________.
slope: d.d*10d (153-154).(155-156)*10[(157-158)]
intercept: d.d*10d (159-160).(161-162)*10[(163-164)]
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MAX517 DAC
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ADT7420 temperature sensor
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AD5161 digital potentiometer
M95080 EEPROM (2 pages)
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