EEPROM .bin Switching

[RyanK]

Just wondering if anyone here is successfully using a .bin switch by switching address lines on a larger eeprom and .bin stacking?

I’m specifically looking at an L67 (blue/pink connector) pcm and thinking about using a 27SF020 or a 29F040 and having either 2 or 4 different tunes.

I’m just trying to figure out what pins I need to switch to make it work.

[antus]

the ecm nvram bin_sw jumper does this, but it can cause crashes of the ecm so its best only done when the engine is not running. that system also has map_sw to a GPIO line that can do it in software to avoid that problem. That's not to say it cannot be done, but you might need to come up with something that can do it quickly enough that it doesnt glitch any read transaction from the eeprom. even though the data is the same, the eeprom wont like you changing the address pins mid transaction so a read might fail which can be enough to crash the pcm.

[RyanK]

Thanks for the reply.
Yeah I noticed the NVRAM I have has a .bin switch on it.
I use that NVRAM for tuning though but am more looking at an option to have even more tunes on an eeprom after they have been finished on the NVRAM
I’ve read on this forum about it being done on a smaller .bin but not in one large enough for an L67 pcm.
I guess if anyone could help with some information on how to work out what address pins to switch I could give it a go and see if I can get something working.
I’ve found it’s normally the upper address pins but have seen some different information too.
I may just get both of the chips I mentioned and test them switching just the highest address and flash tunes on with just a higher idle speed to see what .bin it selects.

[antus]

Its the pins numbered higher than where you have anywhere to connect them to. Just off the top of my head but to give you some ideas.. adjust numbers and details to suit. Say you PCM has up to Address pin 12. Then you would connect address pin 13 through a 10k resistor (known as a pull up) to 5v. And have a jumper that connects it to ground. This will mean that when the switch is off power goes through the 10k to the address pin and it reads high. then you set the switch to connect the pin to ground (the 10k to 5v stays in place) and the power can more easily get to ground than through the chip and so it is 'pulled low' and reads zero. The 10k is still in line which limits current so only a small amount of power goes through and nothing blows up. The state of this pin will define if the pcm sees a 1 or a 0 as the top address pin since the pcm cant control it your jumper does. So it sees the top or the bottom copy of the bin. Add another pin with the same logic and you get 4 banks. Digital circuits can read differently for 1 or 0 with high or low. So you'll need to test which bin is seen by the pcm by putting different cals on each bank and reading back over aldl to see which one you are looking at to map it out and know if the pcm considers high or low 0 or 1.

[RyanK]

Awesome. Thank you.