CAN transceivers for TI Piccolo

Hi Hemanth,

The nice thing about the PHY layer of CAN is that the transceivers are fairly interchangeable. All CAN transceivers will have TXD and RXD lines that are shared with the CAN controller, which in your case is built into the TI Piccolo device. Then in addition to those two lines, some transceivers will have an additional mode pin .

It looks like you have an automotive application, since you posted this question in this forum. That narrows down the recommendations to only our automotive qualified tranceivers (not industrial). Also, I beleive all the Piccolo microcontrollers are 3.3V micros, so you will also want a device that has level shifting or 3.3 volt compliant I/Os. Are you interested in SILENT mode or STANDBY mode? That will also help narrow things down more.

In terms of your second question. I would recommend placing that question in the forum below. I am not familiar with which Evaluation Modules that have that have CAN transceiver already populated.

http://e2e.ti.com/support/microcontrollers/c2000/f/171.aspx

Thanks,

John

Hi John,

Thanks for the information.

I had doubt regarding the Silent mode.

1. Silent mode as I understood is receive only mode?

2. Does it acknowledges for all the CAN frames in the Bus?

3. Are there any significant advantage on usage of this mode?

4. How is Standby mode different from OFFmode?

regards,

Hemanth

Hi Hemanth,

Please see my feedback below.

1. Silent mode as I understood is receive only mode?

• Yes, that is correct. The driver is disabled and the normal receiver remains active.

2. Does it acknowledges for all the CAN frames in the Bus?

• No, a device in SILENT mode will not acknowledge any bus frames, or send any error frames when corrupt messages are on the bus. It's driver is completely disabled.

3. Are there any significant advantage on usage of this mode?

• I have seen the mode used for diagnostics, and for applications where the node never has to transmit any information. One example I have seen is in a gauge application in the instrument cluster of a vehicle. The gauge only needed to receive information, it never needed to transmit anything. Therefore, from a system standpoint, you can guarantee the device will be silent if the device is forced into SILENT mode, and it will not contribute to using up any available bandwidth on the bus.
• If you look at look at the SN65HVDA1050A-Q1 device, or the SN65HVDA542-Q1 device (which are the only two automotive qualified CAN transceivers with SILENT mode), you can see that there is no power savings over normal mode in the recessive state vs. SILENT mode.

4. How is Standby mode different from OFFmode?

• In some cases there is no difference. We offer two types of STANDBY mode. One with remote bus wake-up and one without. In both cases the driver is disabled and the normal receiver is disabled. This means that the device is a lower power mode. In the case where there is remote bus wake-up (meaning activity on the bus will trigger a wake up request via RXD to the microcontroller) there is a second lower power receiver on the device that monitors the bus for activity while in STANDBY mode. If you look at the SN65HVDA540-Q1 or the HVDA551-Q1, while in standby mode the current consumption goes from 10mA max, to 5µA max.

Please let me know if you have any other questions.

Thanks,

John

Hello John,

Thanks a lot for the detailed information. Now I have some doubt on below:

2. Does it acknowledges for all the CAN frames in the Bus?

• No, a device in SILENT mode will not acknowledge any bus frames, or send any error frames when corrupt messages are on the bus. It's driver is completely disabled.

If the transceiver is in SILENT mode, how does it receives CAN frame without actually ACKNOWLEDGING the CAN frame? (i.e. ACK slot has to be set by the receiver of the CAN frame)

regards,

Hemanth

hi John,

Thanks a lot for the clarification

Regards,

Hemanth