TMS320F28035: eCAN problem with different part numbers

Ahmet OBALIOĞLU

Part Number: TMS320F28035
Other Parts Discussed in Thread: AM3354, C2000WARE

Hello,

We have a product that has been working with F28035 for 4 years. We encountered a problem in our last production. CANBUS works for a certain period of time in all products in the last production and then falls into error and the bus is turned off (CANGIF0 = 0x00002700). After searching for the cause of the problem for a while, we replaced the F28035 with the ones that were used in the previous production.
We saw that there was no problem on the same card as the F28035s we used in the previous production.The F28035s used in the new production look like revision 0 and the F28035s used in the old production look as revision A. You can find the pictures below.

Used in new production (CANBUS problem experienced)

Used in old production:

Do you have any suggestions for the problem?

Thank you

over 6 years ago

0 Hareesh Janakiraman over 6 years ago

TI__Guru* 95315 points

What is your clock source? What is your CAN bit-rate?

0 Ahmet OBALIOĞLU over 6 years ago in reply to Hareesh Janakiraman

Prodigy 120 points

Hello,

We are using internal oscillator 1 as Clock Source(60 MHz) and CAN bit-rate is 1 Mbps.

0 Hareesh Janakiraman over 6 years ago in reply to Ahmet OBALIOĞLU

TI__Guru* 95315 points

Do you perform the Oscillator Compensation function as outlined in http://www.ti.com/lit/an/sprabi7a/sprabi7a.pdf?
What is your bus length and how many nodes do you have?
Have you looked at the Debug tips in SPRA876?

0 Ahmet OBALIOĞLU over 6 years ago in reply to Hareesh Janakiraman

Prodigy 120 points

1. No, but revision A MCUs are working on the same PCB.

2. We have a single node (AM3354) of bus length is ~5 cm.

3. Yes,

We see that the CANTEC registers increase and the following bits are set respectively in the CANGIF0 (0x2300) variable and finally the bus closes by setting the BOIF bit in CANGIF0 register (0x2700).

WLIF0/WLIF1 Warning level interrupt flag 1 At least one of the error counter

EPIF0/EPIF1 Error passive interrupt flag

WDIF0/WDIF1 Write-denied interrupt flag

BOIF0/BOIF1 Bus off interrupt flag

0 Hareesh Janakiraman over 6 years ago in reply to Ahmet OBALIOĞLU

TI__Guru* 95315 points

If you are using the internal oscillator, you must perform Oscillator Compensation to be able to use the CAN at 1 Mbps. This is independent of the silicon revision you are using. Without temperature compensation, the oscillator accuracy cannot support CAN operation at 1 Mbps. Please see SPRABI7 for more details.

0 Ahmet OBALIOĞLU over 6 years ago in reply to Hareesh Janakiraman

Prodigy 120 points

Thanks a lot for the answer, I'll try reducing the CANBUS speed to 500 kbps. Does the problem occur at 500 kbps?

It has been very interesting for us to work this way at 1 Mbps for a long time in many locations and to see the problem in only the all devices in last production.

0 Hareesh Janakiraman over 6 years ago in reply to Ahmet OBALIOĞLU

TI__Guru* 95315 points

This has nothing to do with the bit-rate or even CAN operation. The frequency of the on-chip oscillator is sensitive to temperature variation. Please refer to page 36 of SPRS584M. Table 5-7 shows 10 MHz to be the TYPical frequency, not the absolute frequency. The note under the table clearly says the following:

(1) Oscillator frequency will vary over temperature, see Figure 5-9. To compensate for oscillator temperature drift, see the Oscillator Compensation Guide (http://www.ti.com/lit/an/sprab84a/sprab84a.pdf ) and C2000Ware.

Fig 5-9 shows the frequency movement with temperature. To ensure osc accuracy over the temp range, compensation is a must.

With lower bit-rates, you may be able to get by without compensation. However, there are other peripherals that may be impacted by the change in frequency.

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TMS320F28035: eCAN problem with different part numbers