Informations about ESP32 embedded processors

[Yaroooo]

Dear Sirs,

I've recently discovered this module announcement and I've a question about internal processors. I suppose that there is one processor dedicated to wifi tasks and one as MCU, that is correct? I want to ask if either processors are programmable and if it's possible to directly access to wifi processor. I've this question since I've tried some of wifi SoC units, but since embedded WiFi processor was only accessible by internal second MCU there was delays between gpio and peripheral sampling that negatively affect wifi rate and delay.

Also, I've an additional question about Beta testing, if it's still accessible and who is eligible.

Thank you.

[ESP_Sprite]

At the moment, the SDK only supports the first processor of the ESP31. As soon as the ESP32 is out, the plan is to move to a SMP system, meaning that it basically will act the same as a dual-core PC, that is, you just start up a bunch of threads which will be pinned to one of the cores or allowed to run on whichever core has the most time free. Because both CPUs have a shared memory region, there should be no difference in running the WiFi stack on one CPU and the app thread on the other, or running both on the same core. (I think the existing dual-core systems you're referring to are the ones with a dedicated WiFi chip with a separate microcontroller chip connected to it: these tend to have higher latencies because of the slow communication path between the two.)

For the beta program, I think it is closed by now... you can always try mailing beta@espressif.com though.

[Yaroooo]

Thanks for your answer. As I understood form forum post there is two type of ESP models; ESP31 and ESP32. They'll both reach the market or ESP31 is the first "beta" version? Can you tell me more informations about this?

There is two processors that have multiplexed periphericals and both can access to all pins and periphericals, so both have also possibility to access to RF circuitry?

[ESP_Sprite]

As I stated before, the ESP31 is a sort of engineering sample. It will be 99% identical to the ESP32, but we'll be taking the opportunity to tweak a few things before the release of the ESP32. The ESP32 is the one that will end up on the market.

I don't understand your question re 'access to RF circuitry'?

[Yaroooo]

Usually I'm used to see wifi SoC with this structure:



As you said "Because both CPUs have a shared memory region, there should be no difference in running the WiFi stack on one CPU and the app thread on the other, or running both on the same core.". So, regardless of SMP system is used or not, both CPU are able to trasmit to wifi output pin, so it's just an internal pin shared between this two cpu. Just a confirmation of this.

[ESP_Sprite]

Ah, like that. What happens is that both CPUs share some RAM, which is DMA-capable. The WiFi can be instructed to put the data into or read data from this shared memory. So it's not just the single pin that is shared, it's the entire WiFi baseband hardware that is shared.