AEK-COM-ISOSPI1 (L9963T): Unable to get isoSPI Output

[akm_369]

Dear Community Members,

I was exploring AEK-COM-ISOSPI1, SPI to isoSPI dongle, based on L9963T transceiver for one of my new project. I wanted to make use of this interface product for a simulating software that runs on a Teensy 4.0 microcontroller. I have verified that the SPI data is received to the board, but unfortunately no signal was available on the isoSPI end. The setup and scenario is as below:

Teensy 4.0 (at 2MHz, SPI Mode0) acts as Master and I need this board to be on slave mode. Hence, I kept the jumper NSLAVE at JP1=0. The signals at SCK (TP6), SDI (TP7) and NCS (TP8) looks good as expected which was sent from the Teensy microcontroller. VDD and VIO was set to 5V. The other jumper connections are not quite clear to me however I tried few combinations and none of them seems to give me the isoSPI signals. For example, I tried TXAmp =0, TXEN =1, ISOFreq=1, BNE=0 and DIS=0 (JP2-JP6 respectively). I have also measured the signals at the L9963T pins input and all looks good. It seems like the conversion is not working or my setup is not correct.

Could someone guide me where am I going wrong? I am new to this hence any help would be grateful.
Thanks for your time!!

[akm_369]

I would really appreciate any inputs on my above query. I did even tried to give an isoSPI input on the other side, but still couldn't get the SPI output. So both directions doesn't seem to work. 
Also, could someone also share the purpose of jumper JP7 on the board?

[Chronal]

Hi, 

Could you share SPI parameters:

- SPI frequency

- CPOL CPHA (Rising - Falling)

- etc...

Morover, Have you tried with 5MHz spi frequency?

JP7 is used only with AEK-POW-BMS63EN in order to manage Fault coming from daisy chain (Single or Dual access).

If you use AEK-POW-ISOSP1 as tranceiver (Master or Slave) without AEK-POW-BMS63EN, please, remove JP7 jumper. 

[akm_369]

Thanks for the response!
I configured my Master SPI frequency at 2MHz, also tried with 1MHz. The CPOL=0 and CPHA=0 on my Master Teensy, as it was configured for SPI_MODE0.

I read from the manual that on Slave mode it supports up to 10MHz.Ofcourse, I could give it a try with 5MHz as well. But my application was intended to run at 2MHz or 1MHz. 

Thanks for the information about JP7. I confirm that I have not connected it while I tested. Kindly let me know if any other information is required.

FYR: I was using the same example master code from the below library to generate the SPI signals from the Teensy. I hope this helps.  https://github.com/tonton81/SPI_MSTransfer_T4

[Max VIZZINI]

Hi,

Not all SPI drivers are the same and minor differences in the protocol timing might lead to communication issues.

Considering that we do not support Teensy 4.0 microcontroller, we cannot debug the actual communication messages and timing generated.

To help you with the process, I suggest you take AutoDevKit Studio example and verify the messages generated on our microcontroller and then you can compare to spot the difference with yours.

Best Regards,

AutoDevKit Team

[Max VIZZINI]

I forgot to mention that there could be also an issue of endianess.

Our microcontroller is big endian while, I guess, the ARM you are using in little endian.

Best Regards,

AutoDevKit Team

[Chronal · Accepted solution]

Hi,

following my suggestione:

1) Set ISOFreq = 0 and after first spi sending switch to high frequency if needed.

(Note: see pag. 11 of L9963T User Manual)

2) Set CPOL =0 and CPHA = 1 in case of NSLAVE = 0 

(Note: see pag 26 of L9963T User Manual)

3) Make sure you comply with spi elettrica parameter.

(Note: see pag. 26/27 of L9963T User Manual)

4) Make sure you comply with ISO Twakeup before sending spi frame.

(Note: see pag. 24 of L9963T User Manual)

thanks.

[akm_369]

Hi @Chronal and @Max VIZZINI,

Thanks for your inputs!!

I have tried as per your instructions as below:

1. NSLAVE= 0, ISOFreq = 0, BNE/CPOL = 0, TXEN/CPHA =1 (Attached a setup screenshot below)
   Other Jumpers: TXAmp=0, DIS = 0 and disconnected JP7. As earlier, SCK (TP6) , SDI(TP7) and NCS(TP8) are received and correct. Even though, I could see a 1v signal for ISOP and ISOM with respect to GND, their differential isoSPI signal (TP2-TP3) is still nothing.
2. The SPI is already sending the data with MSBFIRST endianess after bit ordering. However, I guess it shouldn't affect the transceiver L9963T by anyways. Sorry if my understanding is not correct.
   
3. I did also tested with 5MHz. Unfortunately, same result.
   
4. Verified the electrical parameters and TWakeup and looks good to me. Not sure where did I miss something.
   

Hence, I would like to inform you that the problem is still not resolved. Later today I will also try to do with AutoDevKit Studio example.

Thanks 
Anand