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### #9 Design a Handheld POV [Post Homework Here]

Posted: Thu Aug 21, 2014 7:43 pm
A new lesson was posted today:
http://www.pyroelectro.com/edu/fpga/handheld_pov/

### Re: #9 Design a Handheld POV [Post Homework Here]

Posted: Fri Aug 22, 2014 8:56 pm
The homework looks like the one from lesson8

/Bingo

### Re: #9 Design a Handheld POV [Post Homework Here]

Posted: Sat Aug 23, 2014 9:34 am
Bingo600 wrote:The homework looks like the one from lesson8

/Bingo

I'll fix this + the schematic PDF (it says lesson8 as well) on sunday. Sorry

### Re: #9 Design a Handheld POV [Post Homework Here]

Posted: Mon Aug 25, 2014 5:53 pm
Seems like the schematic is fixed , but not the homework

/Bingo

### Re: #9 Design a Handheld POV [Post Homework Here]

Posted: Mon Aug 25, 2014 7:41 pm
Bingo600 wrote:Seems like the schematic is fixed , but not the homework

/Bingo

They're all fixed now!

### Re: #9 Design a Handheld POV [Post Homework Here]

Posted: Tue Aug 26, 2014 6:44 pm
HOMEWORK QUESTION 1
Modify The ROM in lesson10’s VHDL code, so the POV message will be: HELLO!

I suppose you mean lesson9's ....

Code: Select all

`   type num_array is array (0 to 31) of std_logic_vector(7 downto 0);   constant led_message : num_array := (      0  => "00000000",               --      1  => "11111111",               --********      2  => "00010000",               --   *      3  => "11111111",               --********      4  => "00000000",               --      5  => "11111111",               --********      6  => "10010001",               --*  *   *      7  => "10000001",               --*      *      8  => "00000000",               --      9  => "11111111",               --********      10 => "10000000",               --*      11 => "10000010",               --*      12 => "00000000",               --      13 => "11111111",               --********      14 => "10000000",               --*       15 => "10000000",               --*      16 => "00000000",               --      17 => "11111111",               --********      18 => "10000001",               --*      *      19 => "11111111",               --********      20 => "00000000",               --      21 => "00000000",      22 => "00000000",      23 => "00000000",      24 => "00000000",      25 => "00000000",      26 => "00000000",      27 => "00000000",      28 => "00000000",      29 => "00000000",      30 => "00000000",      31 => "00000000"   );`

HOMEWORK QUESTION 2
How would the LED message change, if we used a faster clock signal to the CPLD, from the
555 timer?

I haven't build the pow (blush).
But i'd suppose either :
1: The letters would be narrower , as (with the same hand movement velosity) there is less time where the leds are on.
2: The on time would be so fast so it would look like a blur of red.

HOMEWORK QUESTION 3
What is a good clock frequency to use when building a hand-held POV? Why?

200Hz (5ms) - (video says 5us ... thats a tad fast for 200Hz)

At 200Hz the flicker isn't visible to the human eye.

/Bingo