Hardware Alternatives

[Mike-K8LH]

If it helps... After trying the I2C '23017 chip for an address latch, I ended up using a pair of 74HC574's in cascade which is much faster than designs using serial-to-parallel chips. It takes a little over 3-us to load the address latches. Here's an example Arduino code excerpt;

 /***************************************************************************
  *  write address to the cascaded 74HC574 latch ICs (hi address first)     *
  *                                                                         */
  void putAddr()                              // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  { putData(addr.hi); oe(0); oe(1);           // load 'hi' address byte
    putData(addr.lo); oe(0); oe(1);           // load 'lo' address byre
  }                                           // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /***************************************************************************
  *  write 'data' byte onto the data bus                                    *
  *                                                                         */
  void putData(byte data)                     // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  { busOut();                                 //
    PORTB = (PORTB & 0xFC) | (data >> 6);     // set D7..D6 pins
    PORTD = (PORTD & 0x03) | (data << 2);     // set D5..D0 pins
  }                                           // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[coronax]

Hey, I really like the like the looks of that design. When I was getting started I think that kind of use of the 574s would've really confused me, but I've used them a lot recently in the P:65 expansion bus, and after a few missteps I think I've got the hang of them. The 23017s were a lot simpler to figure out for a novice, but the speed of the i2c bus is definitely a disadvantage now that I'm thinking about larger memories.

[Mike-K8LH]

Hi Christopher. I could send you one of those PCBs if you'd like but they're meant to go onto an Uno clone with a mini, micro, or type-C USB connector (available from any number of AliExpress vendors). You could probably use a 'standard' Uno with some tape or something to keep the jumper block from shorting out on the big honkin' USB connector. My Uno software is clumsy and unfinished but I doubt you need my help in that area.

Cheerful regards, Mike