Interfacing MM5451

[Guest]

I'm looking at the datasheet on how to use this and its only got DATA IN and CLOCK IN. Now it says it uses Serial data input, so what exactly does this mean? SPI?

[Mark]

It means that you clock the data into the chip. 1 start bit and 35 data bits. See the 74595 driver to see how to clock in data. However, there is no enable for the chip like the '595.

[MGP]

If you look on Page 4 of the datasheet you'll find a section called "Functional Description". It has several paragraphs that explain exactly the theory of operation of the chip and how it works. It also has a detailed timing diagram that shows the relationship between the clock and data signals to the device.

They put these sections in the datasheets to answer questions just like yours. ;-)

Once you read and understand how the device works you'll see that SPI can be used to clock data into the device or that you could also "bit bang" the data. The choice is yours. I've used this particular device (it's pretty ancient) in the past, although not with a PIC. I've driven it both ways and it works just as the datasheet describes.