Larry's Blog

PARALLEL & SERIAL MEMORY CHIPS

Here is the very interesting story about 2 kinds of memory chips. One is a parallel type and one is a serial type. The serial memory on the right has only 8 pins. The traditional memory chip has 15 pins for address, and 8 pins for data. Obviously to access this chip, a lot of wiring is needed! Then how can the 8 pin chip be accessed? The answer is by sending a serial stream of data to it. This serial stream might be as follows:

command to write, part of address, other part of address, data to be written

This would be 4 bytes of info sent to the memory chip, along with a clock pulse on another line to guide the reception of the info.

So, can you see the tradeoffs?! The chip with all the pins is heavy on HARDWARE and wiring. The chip with the few pins is heavy on SOFTWARE and intricate programming.

Well, I opted for the small serial chip which can hold 4096 bytes of info. I had to grapple with the intricacies of software. I discovered that I had a bad solder connection on the CLOCK line SCK going from the PIC to the mem chip. I finally have it under control and have dozens of plans for usinbg it. By the way, this is an EEPROM chip. It is a non-volatile memory, but you can write over it up to one million times. These chips only cost about a buck.