The UART of the KM34

[小勇邹]

Can the UART of KM34 work in the DMA mode? If yes, is there any example?

[小勇邹]

Hi,

I have used the example "C:\Freescale\SDK_2.0_TWR-KM34Z75M\boards\twrkm34z75m\driver_examples\spi\dma_b2b_transfer\master\iar\spi_dma_b2b_transfer_master.eww" .But the communication result is not successful.What is the reason?

[Robin_Shen]

Hi

Would you please tell us what kind of error you have meet?

I have only one TWR-KM34Z75M, so I don't have another spi instance on othereboard as slave.

Best Regards,

Robin

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[小勇邹]

Hi,

Thank you for your help.The error happens because I have not connected the slave.

Now I have another question.

I transplant the DMA source code to my old project.

There is an error  "No valid CPU defined!" in the file fsl_device_registers.h after the compiling in the my old IAR project.

It happens because I have not define the CPU_MKM34Z256VLL7 and CPU_MKM34Z256VLQ7.

I cannot find where to define CPU_MKM34Z256VLL7 and CPU_MKM34Z256VLQ7 in the example.

Can you tell me where to define the CPU_MKM34Z256VLL7 and CPU_MKM34Z256VLQ7?

[Robin_Shen]

You can find it in the Defined symbols:

Best Regards,

Robin

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[小勇邹]

Hi,

Thank you  very much.

Now I have another question.

How to set the priority level of the “DMA channel transfer complete interrupt”? I cannot find it in the example.

[Robin_Shen]

Please use the API NVIC_SetPriority ( IRQn, priority ).

"Interrupt_handling_KSDK.pdf" can be download from Interrupt handling with KSDK and Kinetis Design Studio.

Best Regards,

Robin

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[小勇邹]

Hi,

Thank you very much.

Now I have another question.

I let the DMA stay in the receiving mode to receive the data from the master.

The steps to let the bug reappear:

1.Start the receiving:

   {

    uint8_t rx0_buf[10],

    uart_transfer_t receiveXfer;

    receiveXfer.data = &rx0_buf[0];

    receiveXfer.dataSize = 10;   

      UART_TransferReceiveDMA(DEMO_UART, &g_uartDmaHandle, &receiveXfer);

 }

2.Restart the receiving again after receiving a frame

void UART_UserCallback(UART_Type *base, uart_dma_handle_t *handle, status_t status, void *userData)

{

        if (kStatus_UART_RxIdle == status)

        {

uint8_t rx0_buf[10],

    uart_transfer_t receiveXfer;

    receiveXfer.data = &rx0_buf[0];

    receiveXfer.dataSize = 10;  

     UART_TransferReceiveDMA(DEMO_UART, &g_uartDmaHandle, &receiveXfer);

        }

}

3.If sending 10 bytes in the master 10 times in 1s period, the receiving is OK every time.

Remark: The frame in the master---AA AA AA 8C 01 80 FB 02 00 01

4.But if sending 20 bytes in the master 10 times in 1s period, there is an error for the receiving. The DMA interrupt does not happen anymore after sending 10 times in the master. It seems that the DMA communication is dead.

Remark: The frame in the master----AA AA AA 8C 01 80 FB 02 00 01 12 12 12 12 12 12 12 12 12 12

How to restore the DMA communication in such case? Thank you.

[Robin_Shen]

Hi

Yes. The UART of KM34 can work in the DMA mode.

Please check the chapter "25.1.1 DMA Request Sources" and "45.8 DMA operation" in KM34P144M75SF0RM.

You can refer the example "dma_transfer" in KINETIS-SDK.

Please search KM34 then select TWR-KM34Z75M and download SDK_2.0_TWR-KM34Z75M.

You can getting start with KSDK reading "How to start with KSDK".

Best Regards,

Robin

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