Download Hardware Test Plan

P08009 Audible Memo Device
2/26/08
Jon Gosliga
Loic Hureau
Jim Varghese
Alex Gorevski
Overview

Hardware Testing
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
Power Supply
Microphone Output
Sampling Frequency
Offset Circuit
Limiting Circuit
Anti-Aliasing/ Smoothing Filters
Output Amp Power
Speaker Output
Keypad Scan
Appendix A
Hardware Testing
Power Supply (AC/DC and DC/DC)


(AC/DC) Measure with scope in AC mode to determine the noise.
(DC/DC) Measure with Multimeter (Proper output values 12V (-12.07 & 12.192)
, 5V (5.15V), 3.3V(3.1V))
Microphone Output Voltage

Connect microphone to circuit, and speak at a normal speaking volume. Measure
voltage from microphone. Use measured voltage as input to Microphone in
following tests. Expected 900mVp-p.
ADC Sampling Frequency



Input the voltage measured in the Microphone Output Voltage test, 1kHz signal
into microphone input of circuit. The reason for using 1kHz is so it will be easy to
see the samples; 8 samples/cycle
Reference Fig. 1 for probing the DAC.
Press the run/stop button on the oscilloscope and verify there are 8 samples/sec.
Probe with oscilloscope to measure
input signal. Probe output to measure
ADC input voltage.
Probe output of
DAC with
oscilloscope
Input 1KHz Signal
with signal
generator
MIC
AMP/FILTER OFFSET/LIMITER
ADC
AMP/FILTER
SPEAKER
DAC
Figure 1 – System Level Block Diagram w/ probing suggestions
1
Offset Circuit

Apply increasing sinusoidal voltages ranging from 0-3.3Vp-p into the microphone
input at 800Hz (the mid-range of the BPF, will have greatest response)
 Measure to verify voltage range at offset output (limiter input) does not go
negative.
Audio Input Limiting Circuit


Apply voltage that was measured in Microphone Output Voltage test, 800Hz (the
mid-range of BPF) signal into the microphone input.
Measure voltage entering the ADC with oscilloscope. When max input (3.3Vp-p)
is applied, verify that ADC input voltage fully spans 0-3.3V without clipping.
Also, when a larger voltage is applied it should clip the output. Likewise, there is
a sinusoidal output for an input voltage up to its max input (measured in
Microphone Output Voltage test).
Anti-aliasing/Smoothing Filters (frequency response)




Apply the voltage measured in Microphone Output Voltage test into amplifier in
stage 1 (reference figure 3 for stage location) at the following frequencies: 20,
40, 60, 80, 100, 200, 400, 600, 1000, 2000, and 3000Hz.
At each frequency, measure filter input and output voltages (reference figure 1
for probing locations), collect data, and plot in Excel.
Plot points logarithmically (frequency on x-axis, ratio of output/input on y-axis).
An example of a theoretical BPF response is shown in figure 2. Look for roll-off
at lower frequencies (<20Hz) as well as high frequencies (>2000Hz). Greatest
Response will be around 1000Hz.
Determine cutoff frequencies from plotted magnitude response.
unity gain
20Hz
2000Hz
Figure 2: Theoretical Bandpass Filter Response
Output Amp Power (this test was rendered unnecessary due to external speaker)



Input a 3.3V, 800Hz (mid-range of BPF, will have greatest response, and thus
most power) signal into the second stage of the circuit (shown in figure 3)
Measure the peak voltage of power amp that is being delivered to the speaker and
determine RMS power from measurement. (Help determine Amplifier Quality,
size of gain)
Determine impedance of speaker at frequency that was input. (Used for
determining max allowable voltage to speaker)
2
Input signal from
signal generator
MIC
Measure output
Voltage of amplifier
AMP/FILTER
AMP/FILTER/
OFFSET/LIMITER
ADC
SPEAKER
DAC
Stage 2
Stage 1
Figure 3 – System level block diagram, stage designation
Speaker Output (frequency response)


Input to the speaker, a 3.3V variable frequency to determine audible range.
Recommended frequencies: 20, 40, 60, 80, 100, 200, 400, 600, 1000, 2000, and
3000Hz.
Use a dBmeter to measure the output of the speaker volume, record data and plot
response with respect to frequency.
Keypad Matrix
 During normal operation all keypad output pins are set to 0V, and once a button
press is detected a keypad scan is initiated. When the button is pressed the output
should be set to 5 V, and when released, set to 0V. The output should be a square
wave. Verify this result.
3
APPEDIX A
Members:
Alex
Gorevski
Jon Gosliga
Jim
Varghese
Loic Hureau
P08009 -- Audible Memo
Device Phase II
Specifications Document
Ideal Value
11
12
13
Marginal Value
2
1
16
17
3.3
1
1
Unit of Measure
4
5
6
7
8
9
10
Importance
3.4
1
1
Metric
Customer
Needs Number
Specification
Number
1
2
3
9
3
3
dB
sec
sec
20 - 80
60
20
60 - 70
60
60
9
9
9
3
3
3
3
# of memos
MB
dB
$
samples/sec
MHz
kbytes
40
< 95
~ 800
8000
10
500
42
>400
0 - 85 range
< 500
> 8000
>50
-
1
1
3.4
Selection Audio Feedback
Message duration
Message appendature
Additional memo storage
(not schedule or date
related)
Memory
All sound levels
Cost
Sound quality
Processor Speed
Processor on-board memory
Processor Programming
Language
Processor Address Lines
Speaker Output
1
9
9
Bits
dB
C / C++
32
0 - 85 range
14
15
3.4
3.4
Speaker frequency range
Speaker Size
9
1
Hz
in
16
17
18
3.4
3.4
3.4
Mic Frequency Response
Mic sensitivity
Mic size
3
9
1
Hz
dB
in
Assembly
-< 95
400 1.75k
-400 1.75k
---
19
20
1
12
Keyboard processor
capability
Power Supply (AC-DC)
3
3
kHz
V in / V out
8
-
21
12
Power Supply (DC-DC)
3
V in / V out
-
-120Vac / 12Vdc
12 Vdc/ (-12, 12, 5, 3)
Vdc
22
3.4
9
kHz
3
-
23
24
25
3.4
12
12
9
3
9
kHz
dB
dB
3
---
45
0 - 85 range
26
3.4
9
kHz
8
16
27
3.4
9
kHz
8
16
Antialiasing (input) Filter
Roll-off Frequency
Smoothing (output) Filter
Roll-off Frequency
Input Amplifier AGC range
Output Amplifier Power
ADC max sampling
frequency
DAC max sampling
frequency
200 - 2k
2 by 2
200 - 2k (10k max)
45
2x2
4