Hi, i’m trying to achieve switching between two am29bl802 chips by turning low pad on pcb, in my head i think they can be connected parallel except enable pins i’m i correct? i’m planning to use some kind of optic coupler… Can someone who knows more than me advice me? thanks

 

Yes. Connect them in parallel except for CE. Then use CE to switch in the one you need. Usually CE comes from the address decoder.

 

For what do you want to use an optocoupler? For the CE-Signal? For that they are much too slow. Just connect everything in parallel (address, data, RD, WR) and use 2 different CE-signals based on the higher address bits. The easiest way could be using A19 for the first flash and A19 inverted for the second flash, depending on your other required CE-signals (e.g. for RAM)

 

Show us your schematic, A19 and A20 and any address decoder if used.

 

The use will be for switching between two maps on edc16 ecu, i saw a few people done this but they shut down production for low demand. i have got pictures of pcb the big black component is optocoupler i think i can also see transistors but i can’t recognise the rest …

 

I think you have a blue board with two memories, but you can only buy a board with one memory now. Right?
Do you have any information on the white connector. I am looking for the pinout. Information like Pin1=A12.
The CE pin is the one that turns on/off the memory. That is the only pin that is different.

I do not understand why there is an opto isolator. Do you have a picture of the single memory board?

 

AM29BL802 is 8 Megabit (512K x 16) flash memory.
For 512K addresses, it takes 19 address bits, labelled A0 - A18.
If there are two AM29BL802 chips on board, it is possible that they are organized as 512k x 32.
Otherwise, it could be 1 M x 16, in which case they are already using A19 to select CE.

What is it that you are trying to do?

Edit: Made correction to flash memory as per @dl324

 

AM29BL802 is 8 Megabit (512K x 8) SRAM.

AM29* is Flash memory. AM29BL802 is 512K x 16.

 

They are used individually. non modified ECU has just one chip 512kb=1fuel map. i’m trying to achieve desoldring original chip and replacing it with first pcb that will act as extension to second pcb with 2 chips. by enabling first chip and disabling the second chip that will be Fuel map 1 by flipping the switch i want to switch to chip 2 -fuel map 2

 

Unless I am missing something the opto is probably there because the switching between to the two chips is a manual operation and only occurs occasionally. It wouldn't have to be fast and if there is a switch mounted somewhere in the vehicle, protecting the input to CE with the opto seems eminently reasonable.