TCAN4551-Q1: SPI write/read issue

Vincent Chen64988

Expert 4480 points

Part Number: TCAN4551-Q1
Other Parts Discussed in Thread: TCAN4550, TCAN4550-Q1

Hi Team,

My customer built a TCAN4551-Q1 board and is developing FW code. Now they face a strange SPI issue.

Here is SCH.CAN FD上板原理图-TCAN4550-0417.pdf

MCU part # is UIS8910DM, customer refer to "TCAN4550 Demo Software" for developing code. SPI clock is 2MHz.

Customer said they can read Device ID(16'h0000 to 16'h0007) without problem, but they cannot access other registers. They also tried to access Test Register "h0808" but still fail.

Below is the waveform of writing A5 A5 00 00 to reg0808.

Waveform of reading reg0808 .

The read/write waveforms seems no problem, I cannot find any abnormal and it meets CPOL = 0, CPHA = 0. We can find Interrupts register h0820 shows SPIERR and GLOBALERR error but I don't know which failure cause this error.

Besides, customer implement TI's demo code and below is the read/write result.

Please comment this issue and let me know if any experiment we can try.

Thanks very much.

Vincent Chen

over 4 years ago

0 Eric Schott1 over 4 years ago

TI__Guru 53555 points

Hi Vincent,

The Device ID and Interrupt/Diagnostic registers ('h0000 - 'h000C) are accessible even when the crystal oscillator is not present. All other registers and memory ('h0800 +) require the oscillator signal be present to be accessed.

Since it looks like you're able to consistently read the diagnostic registers, I don't expect there is an issue with the SPI coming from the MCU. I would recommend checking the crystal signal to make sure that this is operating as expected. Note that TCAN4551-Q1 was evaluated with the NX2016SA with 8.2pF load capacitors.

Let me know what you find out from checking this.

Regards,
Eric Schott

0 Vincent Chen64988 over 4 years ago in reply to Eric Schott1

TI__Expert 4480 points

Hi Eric,

Thanks a lot for your support. The issue is solved due to the VIO power is 1.8V, that not allow to use a crystal.

May I know if TCAN4550, TCAN4550-Q1 has similar limitation? Because I only can find this description in TCAN4551-Q1 datasheet.

Best regards,

Vincent Chen

0 Eric Hackett over 4 years ago in reply to Vincent Chen64988

TI__Guru 74282 points

Vincent,

The TCAN4550-Q1 does not support VIO down to 1.8V, so this is why this line is not included in the datasheet. The TCAN4550-Q1 indeed has the same limitation.

Regards,

0 Vincent Chen64988 over 4 years ago in reply to Eric Hackett

TI__Expert 4480 points

Hi Eric,

Understood, thanks very much for your description.

Vincent Chen

0 Eric Hackett over 4 years ago in reply to Vincent Chen64988

TI__Guru 74282 points

Vincent,

No problem, if you have any other questions please feel free to create another thread. I am now closing this one.

Regards,

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TCAN4551-Q1: SPI write/read issue