Question about Frank B's memory board

[unicornpower]

Hi,

I'm working on an audio project and have reached the point where I really need more that 64k. I've ordered some of Frank B's memory boards from OSH Park, as I believe these will give me up to 768k? Which should be ample. This will be my first attempt at doing SMD soldering so that should be fun (or incredibly frustrating depending on how it goes). Anyway, I'm struggling to locate the components I need, any help would be much appreciated.

For the memory, I was opting for these I'm not sure if they are jdec, but they are SPI.

For the quad buffers I've found this one

I can't seem to find the 74LCX126 in an SOIC casing, any ideas of a suitable replacement?



For those interested, here's a link to what I'm making..

Cheers,
Scott

 

[PaulStoffregen]

Teensy 3.6 has 256K RAM. Not as much as a fully loaded memoryboard, but probably easier to use. You also avoid the overhead of SPI to access the memory, which could let you create more sophisticated effects.

On those logic chip, be careful about slower chips. The fast LCX ones make quite a difference for 24 MHz SPI.

 

[Frank B]

Teensy 3.6 has 256K RAM. Not as much as a fully loaded memoryboard, but probably easier to use. You also avoid the overhead of SPI to access the memory, which could let you create more sophisticated effects.

On those logic chip, be careful about slower chips. The fast LCX ones make quite a difference for 24 MHz SPI.

I'm with Paul, you'll not get high troughput - They are rated for 20MHz, 20 / 8 = 2.5 MBytes/s , minus some overhead to send addressing-commands. Best case.
On the other hand, for audio, it is more than enough.

The LCX are really needed.

If you have enough free pins, you can use one CS-PIN for every chip (but not with the memory board).
I've used that on my "FlexiBoard" (for T3.6) - Currently, i'm using 4x 23LC1024 as FIFO that way(for my webradio).

 

[unicornpower]

Teensy 3.6 has 256K RAM. Not as much as a fully loaded memoryboard, but probably easier to use. You also avoid the overhead of SPI to access the memory, which could let you create more sophisticated effects.

On those logic chip, be careful about slower chips. The fast LCX ones make quite a difference for 24 MHz SPI.

Thanks Paul, I have a Teensy 3.6 (and 3.5), although I haven't had time to use it yet. I do plan to try my code on that, but suspect 256k is not quite enough. It gives me less than 4s of 12-bit audio. That's certainly a lot more than the ~0.5s I have at the moment though, so we shall see.

When you say logic chips, I assume you mean the buffers not the memory? The buffer chip (the one I could find) is LCX I think? Is the memory I selected suitable? I'm not sure what LCX means..

 

[PaulStoffregen]

The chips beginning with 74 are the logic chips.

The letters in the middle represent the circuit and type of transistors used, and the numbers at the end are the functions. So 74LS126, 74HC126 and 74LCX126 do exactly the same function, but they are made differently and have dramatically different levels of performance. The LCX types are newer technology which is much better. To make this work reliably at Teensy's faster SPI clock rates, you really do need the improved performance.