Quote Originally Posted by Darrel Taylor View Post
Yeah, you've pretty much got it for the SLOW (14.5 minute) version. But I don't think you'll be happy with that. I'd forget about the 10ms per character option, with files that large.

To get any decent response time, you'll need to use the Page Write feature of the EEPROM, unless you are using FRAM, you haven't said.

If you are going to be buying new chips, look at the 18F2520/4520. The 252 and 452 are not recommended for new designs. The 2520/4520 have internal oscillators and several other enhancements. But the best part is that they are cheaper.

Why use the USART?
Cause if you don't, you will probably miss incoming data while trying to write to the EEPROM. With SERIN(2) and full-speed data, there's no time left to do anything else.

I'm using page write, I'm collecting 256 bytes of data into an array then I write it into serial EEPROM. Even with the page feature I would need a ~10ms pause every 256 bytes to have the time to write the 256 bytes array into serial eeprom using the page write. That's why I have to keep the 10ms interval between character from hyperterminal. Any idea? Did I miss something?

I'm chosing 452 or 242 because Norm made an application based on this microcontroler (which costs about 8USD at futurlec.com). It has 28 (or 40) pins, an USART, SPI, 3 (or 5 ports) and can run at 40MHz with 10MHz xtal and PLL enabled. Otherwise if the PIC you are mentioning has the same features and are less expensive AND can be programed with ICSP, why not. I know 425 are supported by my pic programmer, I should check for other models.

About USART, do I need to poll a bit? The program executes the next instruction once the HSERIN is done, no??

I will post my code once I figure out everything about the registers settings.