PCF8583 clock/cal for PE kit

Rsadeika

I just got a couple of these chips, and·I would like to try it·out on the PE kit. The problem I am having is with the actual wiring part, anybody have any ideas as to how it should be wired to be address A1. Since the main eeprom address is A0, I do not want the clock/cal to be A0. I was thinking that pin 3, which is A0, should be left open, meaning nothing is connected, but I am not sure about that. I hope I can get this to be something other than A0.

Thanks

Ray

Peter Jakacki

If you wire pin 3 (A0) high then the device address becomes $A2. The lsb is used for read/write control so that $A3 is the device address + READ which should be handled automatically by the I2C object.

*Peter*

Rsadeika

Thanks Peter

After looking at the data sheet, on the first page, under features -

slave address,

· read A1 or A3

· write A0 or A2

I interpret that to mean pin 3 pulled low (ground), the address would be A0 write, and A1 read. The pin 3 pulled high (5V), the address would be A2 write, and A3 read. In your post when you mentioned A2, and A3, I kind of got lost, but now I think I got it straight. Now, the fun part starts, how do I program for this chip.

The other feature of this chip is the 256 x 8-bit static RAM (32KB). Now, I am wondering, do I treat this like EEPROM or, are their other possibilities with this. The first thing that came to mind was a static ram disk, maybe with eight 4KB file system, or some other combination. Or can this be an extension for the main ram. I wonder what else could be done. This is most likely beyond my capabilities, but, what·the heck.

This sounds like a neat little chip, has anybody used this with the propeller?

Ray

Peter Jakacki

It's an old old chip and with the 256 BYTES of RAM it sucks too much power for me as I run RTCs on tiny 0.1F supercaps which normally will keep the RTC running for a week off power (no problem in commercial systems). I find the DS1302 chips a lot easier to get hold of etc and even though they are SPI I just connect the SCLK to SCL and the I/O to SDA and use one other dedicated pin to select it. The SPI doesn't interfere with I2C (no start/stop etc) and I2C can't interfere with SPI if it's not selected.

I was amused how you interpreted 256 times 8-bit wide RAM to mean 32KB, I wish it was sometimes. The I2C bus is way too slow to consider using for any kind of RAM disk anyway.

*Peter*

Rsadeika

I could of·swore I saw a K after the 256, wishfull thinking on my part. So, this chip is becomming less usefull than I had anticipated. I guess I will have to see how painfull it could become trying to put it to good·use.

Ray

parsko

Rsadeika,

I just wrote an object for that same chip, see this thread

Attached is my code, that I know works. It isn't clean, as I simply wanted to get it going. I do plan to convert it completely to assembly, other than the output. You'll need to use a TV to see it, so if you're hooked up with VGA, it won't work.

I'll be glad to answer any questions, as it took me longer than I am proud of to get it going. I know it pretty well now.

-Parsko

PS - There is a trick to reading it. I highlight the trick in the post above. I hope it will save you the 4 hours I lost to it...