ESP32 Rover module advice.

[djoshi]

Hi All

I aim to use the ESP32 Rover module with the 16MB of flash.

If am correct for all new designs, ESP32-ROVER-E is recommended.

Is there a reason why pins 17-22 are no longer connected for NC?

[ESP_Sprite]

From what I understand, too many people thinking they could use them as standard GPIO pins... they're connected to internal flash and as such have only a very limited use. Making them NC means our support team gets to field a lot less angry calls/emails.

[djoshi]

Ok, I keep them NC.


In regards to GPIO pin, am i correct in understanding that you can program any GPIO to work with UART,I2C,I2S and SPI?

Is there a limit to baud rate or speed?

As I have seen some pins ladled as UART0,UART1 and UART 2?

[ESP_Sprite]

Yes. (Make sure to keep in mind that some GPIOs are input-only, though.) The only exception is if you want to use fast (>26MHz) SPI speeds; you want to route those to the dedicated SPI output GPIOs. The labeled pins you see in some diagrams are either the default pins, or the pins that some SDKs pick for them as the default.

[djoshi]

Yes , I presume that PINs are input are for those ADC pin. I can use these pins a UART RX, would this work?

I might need a fast SPI as I am write to an external SD card.

Is there any limitation when it comes i2c or I2S?

[djoshi]

Where do I find the dedicated SPI pins?

[ESP_Sprite]

Yes , I presume that PINs are input are for those ADC pin. I can use these pins a UART RX, would this work?

Yes, you can use them for anything that does not need output or internal pullup/downs.

I might need a fast SPI as I am write to an external SD card.

Look at the pin description table in the ESP32 datasheet, look for HSPI* and VSPI* signals, and what GPIOs they match to. Those are the pins you want to hook up to for fast speeds.

Is there any limitation when it comes i2c or I2S?

Aside from the aforementioned input-only GPIOs, no.

[djoshi]

Great, i prefer to use external pull up or down. So that is fine.

Just to confirm the fast SPI is still 1 bit of data and to 4 bit mode for SD cards?

[ESP_Sprite]

The SPI interface itself can do quad IO (4-bit), but I don't think it's compatible with SD-cards... the ESP32 has a dedicated SD host peripheral that's actually intended for interfacing with SD-cards; if speed is an issue, I'd suggest you use that.

[djoshi]

You are right the 4 bit is for MMC and not SD card. I will be using standard SD cards and I believe a max speed of 80Mhz can be achieved.
But can this also be reduced for on the same SPI I got other device which do not need to fast speed?

As this is a new board, we aim to design it for max performance.

I will be using the SD card as temp storage for Audio and possibly Videos/Photos in the future.

So what is the difference between HSPI and VSPI. If i am correct VSPI is vertical SPI? Is there any limitation for this? It seems that



Standard SPI and SD card has the following PINS
CS
CLK
MOSO
MISO

While HSPI

HSPICLK -CLK
HSPIQ -- What is this Pin?
HSPID --What is this Pin?
HSPICS -CHIP Select
HSPIWP - Is Write Protection Needed?