MCU-PLUS-SDK-AM263X: Unable to read the data from a SPI slave device using MCSPI on am263x

Ravichandra Sereddy Thipperudra Reddy

Part Number: MCU-PLUS-SDK-AM263X
Other Parts Discussed in Thread: SYSCONFIG

Hi Team,

I am using 'mcspi_loopback_am263x-cc_r5fss0-0_nortos_ti-arm-clang' example code. I see whatever data is transferred on 'gMcspiTxBuffer' is appearing on 'gMcspiRxBuffer'.

For my project I need to read the data back from BQ79600 SPI slave. I sent the read request command and then I tried to transfer 0xFF on MOSI to read back the response. I see the response from BQ79600 on the SPI bus, but the 'gMcspiRxBuffer' doesn't reflect that data instead I see the data i.e transferred on MOSI (same as gMcspiTxBuffer ).

I need your help to guide on what changes I need to do, to avoid loopback and get the valid response data ( from BQ79600 ) in 'gMcspiTxBuffer'

over 3 years ago

0 Ming Wei over 3 years ago

TI__Guru 57715 points

Hi Ravichandra,

That is because you are using the loopback mode. To be able to receive data from BQ79600 SPI slave, you will need to make the following changes in example.syscfg file:

TR Mode: from TX and RX --> RX Only

D0 TX Enable: from TX ENABLE to TX DISABLE

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Hi Ming,

After making the changes you suggested, I see the TX is not working. I think this is expected, as we are disabling TX on D0 ( MOSI )

Below is what I see (TR Mode: RX Only, D0 TX Enable: TX DISABLE), no output on D0 ( MOSI ) line.

After reverting back to the original configuration ( TR Mode: from TX and RX , D0 TX Enable: from TX ENABLE ), I see the below on the bus. Only issue is the data received on MISO line is not copied to ''gMcspiRxBuffer''

Kindly please check and provide your inputs at the earliest.

Thanks,

Ravi

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

Can you try the following?

TR Mode: RX Only

D0 TX Enable: TX ENABLE

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Hi Ming,

I see the below when I set TR Mode: RX Only, D0 TX Enable: TX ENABLE. The command transmitted (TX, MOSI line) on the bus is wrong, repeated 0x80

Regards,

Ravi

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

Sorry, I gave you the wrong SsyConfig settings before. Try the following:

TR Mode: TX and RX

D0 TX Enable: TX DISABLE

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Hi Ming,

I tried it, I see the same results. If possible, please try at your end and provide your inputs.

TR Mode: TX and RX

D0 TX Enable: TX DISABLE

Thanks,

Ravi

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

Unfortunately, we do not have the BQ79600 SPI slave connected to AM263x CC, so we cannot try the SPI RX transfer example.

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Hi Ming,

Ok I understand, let me know if you have any more suggestions.

Regards,

Ravi

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

Can you show us how do you connect the BQ79600 to the McSPI of the AM263x?

Meanwhile we will also check internally how to set the receive only mode.

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

HI Ming,

I have connected the MOSI, MISO, SCLK, CS line from BQ79600 EVM to pin 67, 69, 71, 73 on CC dock card, also I have connected 3V3, GND lines from CC dock to BQ79600, below is the pic for your reference. Also we need to power BQ79600 with 12 V power supply.

For clarity, our requirement is we send the request command from AM263x to BQ79600 via SPI ( MOSI, transmit ) and receive the response back from BQ79600 ( MISO, receive ) on the same channel.

Regards,

Ravi

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

Thanks a lot for your connecting info. We will check internally for solution and get back to you soon.

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Thank you Ming. Kindly let me know, if you have any update on this.

0 Ming Wei over 3 years ago in reply to Ravichandra Sereddy Thipperudra Reddy

TI__Guru 57715 points

Hi Ravi,

I did the similar test as your test except I do not have the BQ79600. Here is what I got:

Set the D1 to be Input in the SysConfig

Set the gMcspiRxBuffer to 0xFF.

for(i = 0U; i < APP_MCSPI_MSGSIZE; i++)
{
gMcspiTxBuffer[i] = i;
gMcspiRxBuffer[i] = 0xFFU;
}

After running the test. The gMcspiRxBuffer was set to 0x00

Here is the Saleae Logic Pro capture:

I think the test result make sense, because the D1 (MISO) has no signal. The test failed because the gMcspiRxBuffer and gMcspiTxBuffer do not match.

By the way, I am using the MCU+ SDK for AM263x 08.04.00.17, example "mcspi_loopback_am263x-cc_r5fss0-0_nortos_ti-arm-clang"

Best regards,

Ming

0 Ming Wei over 3 years ago in reply to Ming Wei

TI__Guru 57715 points

When I run the same example, but with input as D0 (loopback mode), here is the CCS capture:

You can see the gMcspiRxBuffer and gMcspiTxBuffer is the same and the test passed.

Best regards,

Ming

0 Ravichandra Sereddy Thipperudra Reddy over 3 years ago in reply to Ming Wei

TI__Intellectual 910 points

Thank you, Ming for the kind response, appreciate your help. Now I see the response data in RX buffer.

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MCU-PLUS-SDK-AM263X: Unable to read the data from a SPI slave device using MCSPI on am263x