18F4520 and I2C Master

StuartH · Joined: 19 Aug 2005 Posts: 14 Location: W. Midlands, UK

These 4520s of mine seem intent on a rapid and violent journey to the nearest bin! After yesterday's WDT bother, the MSSP module is now playing silly bu***rs - actually, it won't work at all.

Using software I2C, I can make the chip work - but it's not good enough, the application really needs the hardware module. I have the errata document for the 4520 which is liberally sprinkled with references to the MSSP - have these problems affected the CCS implementation of H/W master mode?

I've had no trouble at all using H/W master on 16F877A or 18F452, and it's the same code being run on all 3 processors, no problem there. I've tried PCH 3.203, 3.222 and 3.227. No joy.

Does anyone know if this problem has been resolved in the latest version of PCH? Or do I have to gather up my datasheets and "roll my own"?

MikeValencia · Joined: 04 Aug 2004 Posts: 238 Location: Chicago

Works on a 452, but not a 4520? Those things are supposed to be equivalent!

If i were you, i'd scoop up as much 452 chips as i can from the distros. For all you know, they might make less and less of them and you'll be faced with long lead times.

I'm already experiencing that with 18F448 DIP40s. I guess they want us to go to the 18F4480 soon.

StuartH · Joined: 19 Aug 2005 Posts: 14 Location: W. Midlands, UK

Unfortunately, the distributor I have to deal with has already stopped stocking 452s without warning, hence the change. Oh, and I thought they were equivalent, too! Maybe I'll just prune back the code and fit 16F877s instead.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Digikey has several thousand of each package type of the 18F452.
They sell in several different countries on 3 continents.
http://www.digikey.com

StuartH · Joined: 19 Aug 2005 Posts: 14 Location: W. Midlands, UK

Well, I've got quite a lot of these 4520s, and Digikey seem a tad expensive to me - my company is only a two man outfit and we're not rich enough to take that kind of loss lightly. I've been giving it serious thought though.

However, I've now managed to make the system work acceptably with the CCS software master. It'll do until I figure out how to manipulate the registers directly. I don't have enough time at the moment.