Digital odometer with flash/RAM memory for car

Oh........

P.S.

It needs to store at least 7 digits.......... ie. 123456 and 7th digit is 10/ths km

Thanks!

flash

display

to

except

Anyone?????????????

You need a PIC expert, which I'm not one of. :) There must be someone here who could advise you about how to do this....

Bob

Use the 1000 pulses per km to drive either an interrupt or counter input on the PIC. Increment your main counter every 100 pulses (for 1/10th km). Then maintain the count across 3 bytes (24 bits) which will give you counts up to 1677721.5.

The tricky part will be keeping the value during power down. Flash won't support enough rewrite cycles to be reliable. It's endurance is only typically 10,000 cycles. EEPROM might be better, and most PICs come with a small eeprom memory in them (128bytes in the case of PIC16F628). It's endurance is typically 10 million cycles. Even so, you probably want to keep the circuit powered all the time from the car battery (should draw only a few mA) and have the PIC write the eeprom once a minute or so, provided there has been some change that requires writing.

Thanks for the replies.....

Yeah, I know i need to store the data across a few bytes, but therein lies my problem - i have no idea how to do that.....

Any PIC'sperts who have some example code for storing large numbers in EEPROM ?

Thankyou!

If you're very lucky. But does anyone really think they won't have thrown it in the tip about 20 years before that? In 27 years we will probably have Exa byte memory keys, or Yotta Byte, we certainly won't be using Gigabyte ones. But of course the USB interface will be well and truly obsolete by then as well.

MrT.

I am under impression that current flash memory is rated for at least hundred thousand write cycles, maybe more. So, assuming a case of say,

But, that backing up probably involves writing to some locations many times.

Andy Wood snipped-for-privacy@trap.ozemail.com.au

Hi!

Thanks for the ongoing discussions.......

It looks like I can write to an EEPROM in "page" mode to acheive a longer than one byte storage solution (allows 16-256k data to be written with one command).....well, at least thats what I am interpreting from my recent google discoveries.

Keep the ideas coming!

Thanks to all.....

Don't think you're quite right, though I get your drift. They still (just about) use floppy disks... though perhaps they've shrunk in size. My first was 8 inches.

That's better. Will just about do. I thought it was 10,000.

Why's that?

how things change!

can you remember the last time you used a floppy, or had a product come with drivers on floppy?

I can't remember when I used a centronics printer cable last either.

I'm still using a serial cable label printer, but the drivers are that outdated, I decided to get a USB one, as I always have trouble installing onto a new system, and getting 100% response out of the old RS-232 config. When the lables finish, out it goes.

And let's face it, RS-2332 was great and is still used, but when I look back at all the handshaking we had to take care of, I can see why the average user was very confused, and why config experts made a quid.

USB around in 20 years? Maybe, but it would be more likely another super version. No doubt a wireless LAN for all peripherals. Get rid of the cables, that would be nice.

Don...

:-)

Anyone who knows me well, will know I have been up and working between

Only difference is I better lay off the biccies this time around. :-)

Don...

Best time of the day. My record is 1am, normal is 3.30 am. Go to bed about

Well, it would depend on all sorts of things. If you just copy a whole lot of files to a typically FAT-formatted disk, some sectors in the FAT and directory would get updated over and over again as each file is created.

Some makers of the flash disks claim that they avoid this problem by not simply mapping logical sectors to physical locations in the flash (ask Mr Google about "wear leveling").

Andy Wood snipped-for-privacy@trap.ozemail.com.au