New ESP32 Board Bootloader

[ESP_Sprite]

No. Even if you could make it work software-wise, you would not be able to boot from PSRAM. To be honest, I seriously doubt your designers intellectual capabilities if he seriously believes RAM is a replacement for flash.

[lannocm]

OK

Many thanks for your help.

[lannocm]

Another thought...

Is it possible to 'piggyback ' flash memory as a separate chip?

Thanks

[WiFive]

If you want to mount a flash chip on top of the psram chip and do some micro soldering it might work.

[lannocm]

It doesn't sound like I have anything to lose! Would you be able to help me with what to do?

Thanks

[WiFive]

Really your designer should fix the design and pay for new boards. It's going to be very difficult to solder wires directly to the pins on the esp32 chip and you're going to end up with something messy and fragile. If you don't have an idea of what to do it's probably not worth trying.

[lannocm]

Hi,

I'm waiting for a new design from the designer, who has admitted that he missed the flash chip of the first design. I'm still keen to have a go at fixing the original board and I have more information now about the flash chip to use. I've also done a bit of research and I believe that I now know how to solder in the flash chip but I would like to run it past you guys for verification.

The flash chip is W25Q128JVSIM TR and has the following pin config:

flash chip pin config.png (84.93 KiB) Viewed 6075 times

It shares a lot of the pins with the PSRAM and, according to the ESP32 hardware design, can be multiplexed with all of the pins, with the exception of the CS pin.

PSRAM chip pin config.png (47.21 KiB) Viewed 6075 times

Below is the ESP32 DOWDQ6 pin config. If understand the documentation correctly, pin 30, labelled SD_CMD is what is used to connect to the CS pin on the flash.

ESP32-DOWDQ6 chip pin config.png (51.35 KiB) Viewed 6075 times

So, I have consolidated the information in to a table, which I will put in the next post.

[lannocm]

Here is the table:

I have marked, in red circles, where I think the soldering should be done but I'd be grateful for any thoughts anyone has on what I have said and shown.

Thanks.

Soldering points - part 1.png (369.55 KiB) Viewed 6074 times

Soldering points - part 2.png (167.4 KiB) Viewed 6074 times

[WiFive]

You are on the right track, unfortunately SD# does not map directly to IO#, you should use the SPI labels. Check the esp32-wrover schematic in the datasheet. I don't know if sharing a clk pin is officially supported.

[lannocm]

Ah!

So, I think I have the pins correct but the wrong labels on them. I'll double check that shortly.

As for the clk pin, according to the hardware guidelines, psram and flash can share the same clock, though there is a separate clock on the esp32. At least, that's my understanding.

Also, can you tell me what the difference is between /CS and CS#, please? I get that CS# is inverted but not what /CS is.

Thanks

Screenshot_20210308-194718_Acrobat for Samsung.jpg (435.32 KiB) Viewed 6038 times