Flash Memory

Flash Memory and psram memory

Flash Memory

The Teensy audio shield contains 8 pads that you can solder a SOIC 8-pin flash memory chip to the shield.

You can also use a SOIC-8 pin to through hole pin header to bring out the flash memory, such as the Sparkfun BOB-13655.

You would use the Serial Flash library to access this memory.

Flash memory chips that are known to work with both the audio shield and the Teensy 4.1 include:

• W25Q128JVSIQ-ND, 128 megabit/16 megabyte storage.

Here is a post containing timing information on accessing flash memory vs. SD cards.

You can use Frank Boesing's Teensy Transfer to inspect, write to, and read from flash memory on a Teensy LC, 3.1, 3.2, 3.5, or 3.6 (right now it does not work on a Teensy 4.0):

• Github page with the code
• PJRC thread about TeensyTransfer

In 2020, patches were provided in the thread by Michael Meissner to allow Teensy Transfer to work on the Teensy 4.0 to access flash memory on the audio shield. Teensy Transfer has not yet been ported to the Teensy 4.1 to access the flash memory that can be directly soldered to the Teensy 4.1.

Teensy 4.1 QSPI flash and psram pads

The Teensy 4.1 has two sets of pads to solder one or two 8 pin QSPI flash memory chips directly on the Teensy. One of the pads is set up for a SOIC 8-pin flash (same flash as used by the audio board). The other set of pads has a smaller footprint, and is meant for SOC 8-pin psram memory.

PJRC.COM sells a psram chip for the Teensy 4.1:

• PJRC.com 8 megabyte psram flash chip
• Aliexpress.com 8 megabyte psram flash chip
• Electrodragon.com 8 megabyte psram flash chip
• You can solder in 2 sets of psram chips instead of one psram chip and one flash memory chip.
• If you solder in 1 or 2 psram chips, starting with Teensydunio 1.52, the Teensy startup code will initialize the psram.
• Unlike flash memory, psram does not persist when the Teensy is powered off.
• This post on pjrc.com shows the pinouts of the flash pads underneath the Teensy 4.1.