I need a non-voltile serial memory chip that I can clock random bits(about 500 bits) into one at a time by hand using toggle switch to clock them in . This stored bitstream is then clocked out at 20K bits/second at the push of a button, every time you push this button the chip outputs the same bitstream. Can I do this without having to write any programs? Thank you!


2 Answers 2


Probably not, but then writing the simple code for this in a microcontroller is really easy. EEPROM chips don't work this way because there is more to a EEPROM than just storing and reading back a string of 500 bits. Some SPI EEPROMs come close to what you want once you get going, but there are still issues of pages, opcodes, and the like.

500 bits is only 62.5 bytes, so any micro with at least 64 bytes of EEPROM built in can easily do this. That is a small amount of EEPROM for a micro. This also allows the button debouncing to be done in firmware.

Also, 500 bits by hand? Seriously? The chance of getting those all right is pretty much zero.

  • \$\begingroup\$ @ Olin: Thank you for the reply. Getting all 500 bits entered correctly by hand is trivial for me. I have a perfect system for doing it. I'm an inventor, that's what I DO :-) Can you recommend a chip (micro) for me? \$\endgroup\$ Mar 29, 2012 at 14:18
  • \$\begingroup\$ It really depends on the rest of the application, but considering you only need three DIO pins, you can use a cheap DIP8 part like an ATtiny \$\endgroup\$
    – drxzcl
    Mar 29, 2012 at 15:31
  • \$\begingroup\$ I'm fascinated to know what this is for. \$\endgroup\$ Mar 29, 2012 at 21:30
  • \$\begingroup\$ @ Rocketmagnet: TOP SECRET...... ;-) \$\endgroup\$ Mar 29, 2012 at 21:40
  • \$\begingroup\$ Aw! (plus 15 chars) \$\endgroup\$ Mar 29, 2012 at 21:48

It's possible that the IDT72103 will do what you want.

  • \$\begingroup\$ No it doesn't do what the OP want since it's volatile for one. \$\endgroup\$ Mar 29, 2012 at 21:11
  • \$\begingroup\$ Oh yeah, whoops. \$\endgroup\$ Mar 29, 2012 at 21:13
  • \$\begingroup\$ @OlinLathrop If it didn't have to be non-volatile, a CPLD might be able to do the job. CPLD connections can be entered as a schematic, which would satisfy the "don't write any programs" requirement. \$\endgroup\$ Mar 30, 2012 at 0:24
  • \$\begingroup\$ Nick, CPLDs are non-volatile right? \$\endgroup\$
    – drxzcl
    Mar 30, 2012 at 11:42
  • \$\begingroup\$ @drxzcl If you make a flip-flop in a CPLD, it will be volatile. \$\endgroup\$ Apr 1, 2012 at 5:45

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