SPI Problem at High Temperature

Saleh Ziaieinejad

Other Parts Discussed in Thread: TMS320F2812, ADS1205

I am using a C2000 series TI DSP and I have a problem: When the temperature is high (DSP package temp around 80C), sometimes the DSP does not correctly receive SPI messages. At low temperatures the message that is sent to the DSP (measured at DSP pin) is the same as what the DSP reads. At high package temperature (around 80C), however, sometimes the two messages are different. At temperatures around 110C the two messages are always different. Reading wrong message leads to parity check of the SPI message not being verified. I am wondering what the reason for this issue is (the DSP is expected to tolerate higher temperatures), if this is a common issue, and if there is any solution for that.

over 5 years ago

0 Marlyn Rosales Castaneda20 over 5 years ago

TI__Mastermind 22810 points

Hi Saleh,
What device are you referring to?

Best,
Marlyn

0 Saleh Ziaieinejad over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 30 points

Hi Marlyn,

It is a TMS320F2812.

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to Saleh Ziaieinejad

TI__Mastermind 22810 points

Saleh,
Do you know what the device package is (ex. TMS320F2812PGFA/TMS320F2812PGFQ/ TMS320F2812ZHHS)?

Best Regards,
Marlyn

0 Saleh Ziaieinejad over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 30 points

Thanks for the reply. It is TMS320F2811PBKQ

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to Saleh Ziaieinejad

TI__Mastermind 22810 points

Thanks for the information Saleh.
Now, what device are you talking to? Have you check the temperature range for that device?

Best,
Marlyn

0 Saleh Zia over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Thanks for the reply Marlyn,

It is an RDC chip (AD2S1205WSTZ). We are measuring the temperatures of both devices (DSP and RDC) using thermal couplers. At the same time, we are monitoring the SPI message that is received on the DSP pin and compare it with what the DSP actually reads. At low temperature the DSP reads the message correctly. At around 80C the reading may or may not be correct. At higher temperatures it is always incorrect. Whenever the reading is incorrect the DSP may also show that the parity check is failed.

Yours Sincerely,

Saleh

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to Saleh Zia

TI__Mastermind 22810 points

Saleh,
Is the message incorrect on the DSP pin and also what the DSP actually reads or is it just what the DSP reads that is incorrect?

Best,
Marlyn

0 Saleh Zia over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Marlyn,

The message is correct on the DSP pin, but the DSP read is incorrect. It looks like there is something wrong inside the DSP.

Yours Sincerely,
Saleh

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to Saleh Zia

TI__Mastermind 22810 points

Saleh,
Have you tried running your application with another DSP or have you only been trying the same one?

Best,
Marlyn

0 Saleh Zia over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Marlyn,

I tried changing the DSP. At some temperature the problem appears. Some DSPs have a higher triggering point (maybe around 90C), but the reading becomes bad anyway.

Yours Sincerely,
Saleh

0 Saleh Zia over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Btw while searching online for other people's similar experience I found a thread in e2e for a similar issue with another TI product:

e2e.ti.com/.../407047

I thought this might be a known issue for TI.

0 Mark Labbato over 5 years ago in reply to Saleh Zia

Guru 30330 points

Saleh,

The issue and resolution in your most recent post is not related to what you are seeing here.

It is possible that the timings between the F2812 and the external device are just not compatible. It could be either device that causes violations in the other's timing requirements. For example, at worst case temperature conditions, perhaps a setup or hold time is being violated.

A few questions:
Can you share oscilloscope captures of a low temp and high temp transmission? are the signals being distorted in any way?
You stated in your original post that at high temperature the messages are different. Is this referring to the observed message, or the received message in the SPI?
What is your SPICLK frequency? Briefly looking at the ADS1205 Datasheet, the F2812 is the Master and can use up to 25 MHz. what is the frequency at which the SPI starts working again at 110C? Again, the timing requirements will shift across temperature. the Datasheet provides the clear requirements for the SPI to detect the data correctly.

Regards,
Mark

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SPI Problem at High Temperature