which chip to use with flashable smec?

[crusty shadow]

as the title states, im trying to figure out which chip i want to use to build a flashable smec. at the moment im looking at using a 27c512 type eeprom. i like the idea of being able to store 2 cals on the same chip and toggle between them so if i end up getting gas in an area that doesnt have E85 i can flip a switch and change the cal so i can run on regular premium gas.

now my question is this, when looking at the specs for a lot of the chips, thay have a stated temp range of 0 dec celcius to 85 deg. celcius, response times anywhere from 70 nano seconds up to 250. the 85 degrees part is fine but im not comfortable with using a chip that is only rated for 0 degrees celcius, as it gets much colder than that durring the winter here. i really need somthing that will work from 0 deg farenheight to 180- 200 deg so i dont have to deal with the car not running simply cause its too hot or cold for the chip to work properly. ive also read that using a chip with a response time slower than 150 nano is not reccomended. id really like to use a militaary spec chip, and i have seen others on here say they have em, but ive looked all over and cant find one. i dont mind the extra cost, as long as its not more than say 10-15 bucks each so i can buy a few without killing my wallet. can someone point me in the right direction so i can find what i need?

i also have a question about the relay used in modifying the smec. i cant seem to find which one to use. i dont understand what amp rating , draw etc that i need.

last part of this i need an answer to is the interface itself. i bought a laptop last month, and unfortunately it doesnt have a DB9 serial port, only a 25 pin serial port for a printer. i can still use that with the proper adapter correct? ive read in several places that a usb to serial interface doesnt work properly or is finiky at best and would like to use the serial port if at all possible.ive seen several adapters avalialbe for around 10-15 bucks that i think will work. they just plug in to the 25 pin port and give you a standard db9 port.

i'll be ordering everything friday so id greatly appreciate the help. i dont wanna order the wrong stuff and not realise it till everything shows up on my door and i have my smec torn apart

[turbovanman²]

Subscribed,

[ShelGame]

as the title states, im trying to figure out which chip i want to use to build a flashable smec. at the moment im looking at using a 27c512 type eeprom. i like the idea of being able to store 2 cals on the same chip and toggle between them so if i end up getting gas in an area that doesnt have E85 i can flip a switch and change the cal so i can run on regular premium gas.

I don't think it will work. The bootlaoder used is designed to support the write cycle for the AT28C256 and similar chips. The 29C256 and the 27SF512 type chips need a different write cycle that is not supported by SMECFlash or D-Cal.

now my question is this, when looking at the specs for a lot of the chips, thay have a stated temp range of 0 dec celcius to 85 deg. celcius, response times anywhere from 70 nano seconds up to 250. the 85 degrees part is fine but im not comfortable with using a chip that is only rated for 0 degrees celcius, as it gets much colder than that durring the winter here. i really need somthing that will work from 0 deg farenheight to 180- 200 deg so i dont have to deal with the car not running simply cause its too hot or cold for the chip to work properly. ive also read that using a chip with a response time slower than 150 nano is not reccomended. id really like to use a militaary spec chip, and i have seen others on here say they have em, but ive looked all over and cant find one. i dont mind the extra cost, as long as its not more than say 10-15 bucks each so i can buy a few without killing my wallet. can someone point me in the right direction so i can find what i need?

i also have a question about the relay used in modifying the smec. i cant seem to find which one to use. i dont understand what amp rating , draw etc that i need.

Do you have a copy of the word document - 'SMEC_EEPROM_vs2.doc'? It has a complete list of the parts required. I'd post it here, but it's got pictures in it and it's about 600k over the limit for .doc files.

If someone wants to make it into a KB article or something, that might be good. Not sure if the original author would mind or not...

last part of this i need an answer to is the interface itself. i bought a laptop last month, and unfortunately it doesnt have a DB9 serial port, only a 25 pin serial port for a printer. i can still use that with the proper adapter correct? ive read in several places that a usb to serial interface doesnt work properly or is finiky at best and would like to use the serial port if at all possible.ive seen several adapters avalialbe for around 10-15 bucks that i think will work. they just plug in to the 25 pin port and give you a standard db9 port.

i'll be ordering everything friday so id greatly appreciate the help. i dont wanna order the wrong stuff and not realise it till everything shows up on my door and i have my smec torn apart

The USB type adapters will communicate with the SMEC. The problem is, D-Cal does NOT work with the USB adapters. It must access the hardware directly or something. Also, the 25-pin parallel port is not the same as an RS232 serial port. A 25 to 9pin adapter won't get you what you need.

Does your laptop have any PCMCIA card slots? I'd suggest trying to find a PCMCIA card with a true RS232 serial port on it. They're out there.

Or, you can go over to the D-Cal group and try to hound Derek into re-writing his serial code.

There is another program out there. The guy that wrote it (90turbovan?) is not on here, as far as I know. He's on TD.com and the CHeM group. It does work with the USB adapters. But, it's really designed for the SBEC. I don't know if it will work correctly with the SMEC - but I assume it will. The program is on CHeM somewhere. His program might support the 29C256/27SF512 type chips. I don't know...

[crusty shadow]

huh for somereason i was looking for the wrong chip i guess, in the document its showing a 28c256 chip in there so i'll just do that.
but do you have a source for an industrial duty 28c256 with under 150 nano response time? the cold weather rating of most of the chips ive found so far is what really concerns me the most.
the interface from my laptop, i can just swap out cards, i just wanted to know if i could use what i had. although while parousing digi key i did find a few rs232 to usb adapters with the chip and everything on a board with the 232 chip. would be pretty slick to make a drop in module with that and a standard usb port, would really make things convienient. that would only be possible if somone rewrote some code for us. go pester !