topic Re: Pointer alignment error in MCUXpresso SDK

Pointer alignment error

PitOn — Mon, 02 Nov 2020 14:36:23 GMT

Alignment error in "serial_port_usb.с" SDK_2.7.0_FRDMK64
A project was created on the basis of two projects "hello_word_virtual_port" and the project "shell".

When the project was launched, the output of non-correct data to the console occurred.

The problem is alignment of the pointer to the output.
I solved the problem using an intermediate buffer aligned.

line 862 file serial_port_usb.с

if (needToPrime)
{
if (kStatus_USB_Success !=
USB_DeviceCdcAcmSend(serialUsbCdc->cdcAcmHandle, USB_CDC_VCOM_BULK_IN_ENDPOINT, buffer, length))
{
serialUsbCdc->tx.busy = 0;
return kStatus_SerialManager_Error;
}
}

change to

if (needToPrime)
 {
 USB_DMA_NONINIT_DATA_ALIGN(USB_DATA_ALIGN_SIZE) static uint8_t s_currSendBuf[DATA_BUFF_SIZE];
 memcpy(s_currSendBuf, buffer, length);
 if (kStatus_USB_Success !=
 USB_DeviceCdcAcmSend(serialUsbCdc->cdcAcmHandle, USB_CDC_VCOM_BULK_IN_ENDPOINT, s_currSendBuf, length))
 {
 serialUsbCdc->tx.busy = 0;
 return kStatus_SerialManager_Error;
 }
 }

Re: Pointer alignment error

jingpan — Thu, 06 Feb 2020 17:32:42 GMT

Hi Konstandin,

The write buffer is transfer from application level and it is not checked by any level. Although there is no word in RM say DMA is word alignment, USB driver defined read buffer as 4 byte alignment. I'll make further test and report this problem.

Thanks a lot！

Jing

Re: Pointer alignment error

PitOn — Thu, 06 Feb 2020 21:36:05 GMT

Hi Jing !

Here I do not agree with you.

RM.... Paragraph 46.3.3 Addressing BDT entries.

To compute the entry point into the BDT, the BDT_PAGE registers are concatenated
with the current endpoint and the TX and ODD fields to form a 32-bit address.

Konstfntin/

Re: Pointer alignment error

jingpan — Fri, 07 Feb 2020 16:51:01 GMT

Hi,

But BDT_PAGE register point to the starting location of the BDT, not point to data buffer. ADDR[31:0] field point to the data buffer.

Regards,

Jing