UART over DMA, registers are missing in reference manual

[rahul.b.patel]

As I am trying to initialise DMA for UART communication , I found that few resistors
ex:

UHCI_IN_RST
UHCI_OUT_RST
UHCI_AHBM_RST
UHCI_AHBM_FIFO_RST

are missing in reference manual although these resistors are mentioned in driver library "uhci_reg.h",

also no bit value mentioned for initialising UHCI_DMA_IN_DSCR_REG resistor's.

Can someone help or detailed me on this ?

[Ritesh]

Hi Loboris or Espressif Developer,

I am working with Rahul who has raised query regarding UART DMA registers.

So, Would you please check it from your side and let us know if you find anything?

[Ritesh]

Hi WiFive ,

Would you please check question which has been raised by Rahul Patel and let me know if you have any informations regarding those missing details into Reference Manual.\

They are referring latest ESP32 Reference Manual Document for same.

[ESP_Sprite]

Changed title, 'resistors' is quite the misleading term here.

I'll see if I can take this up with the docs team.

[Ritesh]

Changed title, 'resistors' is quite the misleading term here.

I'll see if I can take this up with the docs team.

Ok.

Thanks for your prompt response.

I will be waiting for your reply on this as soon as possible.

[ESP_Sprite]

Ah, hold on a second, these registers are only hinted at in the header files; you initially lead me to believe our drivers actively use it.

The background of this is that there are a bunch of registers that are there for debugging and/or internal use: their use is not documented, not needed during normal (non-chip-design-phase) operations and not recommended as we can remove these or change their behaviour at any time. They actually shouldn't even show up in the header files; I think the script we use at the moment just does not filter them out yet.

[Ritesh]

Ah, hold on a second, these registers are only hinted at in the header files; you initially lead me to believe our drivers actively use it.

The background of this is that there are a bunch of registers that are there for debugging and/or internal use: their use is not documented, not needed during normal (non-chip-design-phase) operations and not recommended as we can remove these or change their behaviour at any time. They actually shouldn't even show up in the header files; I think the script we use at the moment just does not filter them out yet.

Thanks for you prompt reply.

We had checked DMA initialization sequence for both SPI and I2S but we tried also for UART Communication using DMA and not got any success yet.

So, Would you please check at your side as well and provide me UART based DMA example if any for how to use it?

Let me know if you need anything else from.my side regarding same.

[ESP_Sprite]

I think a colleague of mine is working on an UHCI driver; it will be included into esp-idf when it's done.

[Ritesh]

I think a colleague of mine is working on an UHCI driver; it will be included into esp-idf when it's done.

So, It means UART DMA is not fully supported into current UART of UHCI bases driver. Correct?

So, When it will be included into ESP32 IDF? Do you have any tentative timeline or schedule for that?

[ESP_Sprite]

Well, unless I'm terribly mistaken, there is no UHCI driver in the current esp-idf, and the UART driver does not use any of the UHCI features, so no, there's nothing related to uhci just yet. I can't entirely tell when the driver is scheduled; my guess would be that it's going to go in 3.1.