Speaker responce chart draw? K8055 USB

Kits PC Related Projects
1

hi

I have a K8055 usb interface board.

I need to sample speaker response curves.

Im hoping the analog inputs can handle AC/sound frequencys 80 - 20000 hz 50 watt “music” 25 watt RMS

this is to make a cross over ( responce frequencies for mid and tweeter together)

i was considering using a set of opamps with resister offset inputs for stepped readings on the digital inputs, it would provide a square edged result but work well enough…

all in all i need the readout in excel…

analog or digital.

also will the PWM output produce the sound signal? ive seen people on here playing tunes with it right?

im very UN-experianced with programming so the more help the better… cheers
8) 8) 8) 8)

2

The sampling interval of the K8055 analog and digital input/output and PWM output is 10ms.
You can’t sample or produce frequency higher than 50Hz.

One solution can be to rectify (and filter) the audio signal when feeding it to the analog input of the K8055.

3

square bridge rectify?

ok then i would read a steady voltage rise across my test resistance… ok but i still could do with some help with a excel chart for the readings… ive found :

http://forum.velleman.eu/viewtopic.php?f=3&t=4726&p=16990&hilit=excel+plot+graph#p16990

and

http://forum.velleman.eu/viewtopic.php?f=3&t=7541&p=28403&hilit=excel#p28403

but this doesnt give me access to the PWM output

im not sure what to address and how… cheers

p.s. i have some 555 timers lieing arround so could mock somthing up to modulate

its more the outputing form the pc and into the pc im concerned with…

4

[quote]ok then i would read a steady voltage rise across my test resistance… ok but i still could do with some help with a excel chart for the readings… ive found :[/quote]You have to add a button on the Excel sheet to read the analog input value of the K8055. Every time, when the button is pressed, increment the row on the sheet where the value is read.
Now you just have to step the frequency and press the button after every frequency increment.
You’ll get the list of the data values giving you the frequency response of the filter.
Then just use the Chart Wizard to make the chart.

[quote]but this doesnt give me access to the PWM output[/quote]The PWM frequency is fixed 23.43kHz and the duty cycle is proportional to the corresponding analog output (DAC) value.
You can adjust the duty cycle by changing the analog output value.
The duty cycle is corresponding to the analog output voltage in the range 0…255

By setting the DAC output value to 127 you get the PWM ratio 50%.
In this case the PWM output pulse high time and low time are equal.

Increasing the analog output value the PWM ratio increases.

The PWM output is “active low”.
Increasing the DAC output value the PWM output pulse low time increases and high time decreases.

The PWM output is an open collector output.

You can use the function OutputAnalogChannel to set the PWM duty cycle.

Please see also these threads:
viewtopic.php?f=3&t=6047
viewtopic.php?f=3&t=4057
viewtopic.php?f=3&t=3150

5

ok so how do i do that?

6

Please see: “Add a button and assign a macro to it in a worksheet”
These instructions apply to: Microsoft Office Excel 2007
http://office.microsoft.com/en-us/excel-help/add-a-button-and-assign-a-macro-to-it-in-a-worksheet-HP010236676.aspx

In older Excel versions:
The Controls from the Forms Toolbar can be found via View>Toolbars>Forms. The chosen control can be placed on a Worksheet simply by clicking it on the Forms Toolbar then clicking any cell on the Worksheet. You will then be prompted by Excel to “Assign a Macro” to the Control. This can be done immediately or a later stage.