Hello,
I have a device which contains an ESP32S, a microSD, and set of other components including battery and usb charger. The device is a music player which when turned on plays music from the microSD card.
Now the device is closed with 4 screws and is quite complex to open every time to load more content to the microSD. Of course the firmware is not accessible, and unfortunately there is not a way (that I found yet) to connect this as storage device (via USB) or have access to the microSD from remote.
I also don't want to have the microSD card slot replaced with an extension nor damaging the case.
Any idea on how to access the storage to upload/download files with the constrains above?
What I was thinking is, given there is a bit of space inside of the device, to implement something like GitHub - ardyesp/ESPWebDAV: Wifi WebDAV server using ESP8266 with a spare ESP connecting it to the same battery of the device.
is there a risk to damage the SD or the original device with such a solution?
Pending a photo or schematic I’m unclear about your requirement. But if I have understood correctly you just need easy access to the mSD card? In a couple of my music box projects I made a small slot in the case so that with a pair of tweezers (or a small child) I could remove and replace it easily.
I really appreciate all the answers. @Railroader As soon as I can I will provide a photo as well, nothing fancy, just a pcb board with the ESP32S and an microSD card module soldered SMT.
@Nick_Pyner that would be ideal but, I don't have access to the firmware and I cannot change it. And of course the original firmware is not providing such capabilities.
What if I use SPDT solid-state analog switches like TS3A5018 to disconnect (all the 8 pins) the SD from the original ESP (when the ESP is in sleep mode or off) and connect them to the secondary ESP custom, do the transfer, and change it back?
EDIT:
Digging on the internet I found this old project:
My second attempt: anyone can review schema below please?
The custom pcb will use a ESP32 C3 super mini (ESP) (headers H1, H2) and it will be connected to the music player (HOST) via the connector CN1 (with 5V, GND, RX, TX).
The ESP is using the 5V and supply the 3V3 to the rest of the custom pcb.
CN2 is connected to the microSD slot of the HOST via an adapter (will follow).
GPIO1 should be input and "sense" when high, meaning the microSD is not in use by HOST (in SPI mode) [I might remove this as the device goes in sleep mode, and that would be the moment when I switch the microSD to the custom pcb].
CARD1 is the microSD on the custom pcb that must be connected to th HOST by default: both SN74CB3Q3257PWR must have the OE and S ports LOW so that xA ports are connected to xB1.
When HOST is in sleep mode, the idea is to trigger GPIO3 (SELECT) to high changing S ports to HIGH and commuting xA to xB2 ports, and therefore connecting the microSD from HOST to ESP (via SPI).
As mentioned I cannot test prototype myself the board so I will send it to be produced and assembled directly. For this reason I would really appreciate if someone could validate the schema or advice improvements please.
