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It turns out that all the CS lines must be able to go high because leaving one low by default corrupts the memory on that chip. I have broken out pin 4 on the 74LCX138 to Teensy 4.1 pin 5. Setting this HIGH sends all the CS lines high. It appears I am able to run this board successfully at...

The 74LCX138 has three pins E1,E2,E3 to enable/disable it so that more memory can be added to the same SPI bus. I did not bring them out to the board pins though. It's easy to do in the next rev, but it would consume more digital I/O.

Okay here is the github project. Osh Park link within. I am running 12 of these. I'll let you know when they are ready. https://github.com/studiohsoftware/Teensy41Memory

Okay thank you! I added locations for the pulldowns. Can you please clarify "links to change the device selection lines." Is this just a naming thing, like I should use C0/C1/C2 instead of DO2/DO3/DO4? If so, I agree. Or are you talking about moving to different pins altogether? Once this...

Hi everyone, here is the first draft of the Teensy 4.1 memory board with eight SPI memory chips. The MOSI and MISO connections are different than Frank's Teensy 3.x version, which seems to me to be necessary for the 4.1 I removed the 74LCX126 buffer to obtain all eight output pins on the...

Hi everyone, I would like to extend RAM on the Teensy 4.1 to make a four channel looper. I would like to make a new version of Frank's board for the APS6404L-3SQR-SN 8MB SPI memory chip with 8 chips on it. I am currently using Paul's CS42448_T4_TEST2 board...