[islandlabs] 555 info (MP3 Player?)

Burns, William burns at cshl.edu
Thu Jan 27 06:04:24 UTC 2011

Ok... Maybe a more achievable goal (compared to a 4-bit CPU) would be to make a 555-based audio player?
(somebody tell me if I'm completely insane)

Goal: Using 555s, Read an (SD-Card?) memory, and play audio.
Impossible? Maybe. But Maybe not.

The Bus Pirate can speak SPI protocol. So can SD Cards.
(So we can experiment with reading an SD right away)

Apparently, older SD cards (not SDHC) can deliver 1 byte at a time. (The read block-size can be set to 1 byte) 
The SD card can run at just about any clock rate (0 to 25Mhz)

We'd have to push a few 48-bit commands into the SD-card to get it to start transmitting data.
(that might be a show-stopper)

If getting the SD-card transmitting data is too challenging, we could use an SPI EEPROM.

If we can push the serial data into 8 flip-flop/buffers, and then use the flip-flops to drive a resistor-"array" style D/A converter going to a speaker.. That's audio.

Hmm... or maybe a "normal" (parallel) eeprom would be easier.

SD card fits in floppy edge-connector!

Arduino code to read an SD-card via SPI (no library, no filesystem)
SD Card via SPI pinout

SD-Card's SPI Bus Timing and command set

Using the Bus Pirate and SPI to drive Microchip's 23K256 serial 32K SRAM

Last 2 circuits on page:
555-based flip-flop 1-bit memory
555-based Inverting Schmitt Buffer (NOT gate)

Basic Digital Ripple Counter (with flip-flops)

555 analog tachometer

555 based Gauss Gun

555 based PWM controller
555 PWM (requiring trigger)

A PWM circuit could be driven by a digital potentiometer:

Using SPI to drive an AT25HP512, which is a 65,536 byte serial64K EEPROM

Wiring a PIC to the 25LC160B EEPROM

Using an AVR to read the Melexis MLX90129 via SPI

TI TRF2443 EEPROM SPI Bus Timing


> -----Original Message-----
> From: list-bounces at freeculture.org 
> [mailto:list-bounces at freeculture.org] On Behalf Of Joe
> Sent: Wednesday, January 26, 2011 9:58 PM
> To: 'list at islandlabs.org'
> Subject: Re: [islandlabs] Tonights Meeting
> On Wed, 26 Jan 2011 19:38:54 +0000
> "Burns, William" <burns at cshl.edu> wrote:
> > I saw that today's planetarium outing was cancelled.
> > I assume that means that the StonyBrook meeting is back on (and 
> > hopefully Jonathan confirms that) but I can't make it 
> today, so have 
> > fun everyone.
> We've both been ill since Monday. Temperatures today are 
> finally dropping below 101 F. (S-S-S-N-O-R-K)
> > 
> > Here's something to think about though:
> > http://www.555contest.com/
> > Joe's intervalometer design would be a good entry.
> > FYI: the worlds most useless device is also 555 based.
> > Any other ideas?
> At first, I'd say that there's nothing unusual about a 555 in 
> astable mode and juggling the resistor values to achieve a 
> particular repetition rate plus a certain duty cycle. On 
> further reflection, I guess it's a good example of applying a 
> basic circuit to solve a problem "outside the box."
> Hmmm...555 circuits. This will have to wait until I'm well 
> enough to go back to work, but I've got an interesting 
> circuit I came up with for one of our machines.
> Here's the problem: A pressure-differential switch was 
> becoming flaky because the gold contacts were getting dirty. 
> The pressure differential is usually set between 1/16" and 
> 1/8" water. This is the equivalent of wafting your hand 
> side-to-side over a surface.
> The switch has an almost unlimited mechanical life but a very 
> limited electrical life. The machine it's installed in 
> vibrates from both low-pressure and high-pressure pumps...and 
> we have to make it fail-proof.
> Joe
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