CC1312R: uDMA transfer performance

Emil Tchobanov

Part Number: CC1312R

Hi,

In our application we must connect device with 8bit parallel data port to CC1312 MCU. The device stream about 40kB data bytes as generate strobe STROB signal for every byte when valid data are present on device outputs. Device outputs are connected to 8 GPIO pins of CC1312 MCU. The device generates STROBE signal with configurable frequency in range 3MHz to 64MHz.

The idea is to download about 48kb data bytes from device as fast as possible in CC1312 RAM memory using uDMA module (probably channel 14 - DMA_PROG ping-pong). Every single byte DMA transfer will be triggered by device STROBE signal, connected to CC1312 GPIO pin, configured to trigger single byte DMA transfer.

We use TI-RTOS and CC1312 clock during this transfer will be the maximal possible- 48MHz .

How is the maximal possible frequency of STROBE signal we can use to trigger DMA byte transfer from the MCU IO port to internal MCU RAM memory without to lose data bytes?

Or with another words – how is the maximal expected performance of DMA in this case when MCU clock is 48MHz?

Best regards

Emil

over 4 years ago

0 Elin W over 4 years ago

TI__Genius 14845 points

Hi Emil,

Please refer to the DMA documentation:

Thanks,
Elin

0 Emil Tchobanov over 4 years ago in reply to Elin W

Intellectual 255 points

Hi Elin,

Thank you for your fast responce, but I am not asking how to use DMA driver at this stage.

My question was how often (the max frequency of external pin DMA trigger signal) single byte transfer from DIN31_0 register can be performed when no another DMA chanes are in use @48MHz MCU clock?

Best regards

Emil

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

Based on your description, it seems like the sensor controller might be the best option for you. It's a 16-bit ultra-low power MCU that's independent from the main CPU and power states, so you don't have to worry about the main CPU interfering or timing issues if you are using the sensor controller. Is that something you can use in your application?

Thanks,
Elin

0 Emil Tchobanov over 4 years ago in reply to Elin W

Intellectual 255 points

Hi Elin,

I don't think that sensor controller is good variant when I need high performance.

(it doesn't matter which kernel will process the queries)

The question is what is maximal frequency of external pin DMA trigger request which can be served from uDMA WITHOUT losing data bytes?

Best regards

Emil

0 Emil Tchobanov over 4 years ago in reply to Emil Tchobanov

Intellectual 255 points

Hi Elin,

Do you have answer of my question?

Best regards

Emil

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

Yes that's a good point, I agree that the DMA might be the best approach for this kind of operation.

I'll need some time to look into this, I will let you know as soon as I have an update.

Thanks,
Elin

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

I'm still trying to find the information you are looking for. I'll keep you updated.

Thanks,
Elin

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

Thanks for your patience.

The performance data we have for the DMA can be found in the Technical Reference Manual. Unfortunately, we don't have any characterization data regarding your specific question so I would recommend that use a logic analyzer to check the time from the start of the transfer until it's done. The limit on number of bytes that you can transmit is in the TRM.

Thanks,
Elin

0 Emil Tchobanov over 4 years ago in reply to Elin W

Intellectual 255 points

Hi Elin,

As you can imagine - I am not happy because I have to wait more than 25 days and still don't have answer of my question.

For the measurement you suggest, I have to prepare some test program. To do this I have few questions:

1. Can you send me some CC1312 example code related with uDMA initialization?

2. Can you tell me how to set (API function names) and how is maximal clock frequency i can set for uDMA controller and MCU_AON IO controller? (In this case I have to keep working all RF and other RTOS drivers functionality)

(I ask this, because some of limitations are because TI_RTOS and not because of MCU hardware)

I will be more than happy if this time somebody else or you respond faster of my questions.

Regards

Emil

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

Yes I understand your frustration.

I have sent an example implementation to your field team that you can use as a starting point to get up and running as fast as possible.

Thanks,
Elin

0 Emil Tchobanov over 4 years ago in reply to Elin W

Intellectual 255 points

Hi Elin,

Where did you send this example implementation code ?

(I didnt receive it)

Thanks

Emil

0 Elin W over 4 years ago in reply to Emil Tchobanov

TI__Genius 14845 points

Hi Emil,

I sent it to Eran over email earlier today.

Thanks,
Elin

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CC1312R: uDMA transfer performance