SN65DSI83: SN65DSI83 I2C communication not working

Hi Gabriele,

What address I2C are you reading from? Since the ADDR pin is pulled up here, the read address should 0x58 (8-bit). Please try reading from this address.

Best regards,
Ikram

Hi Ikram,

Based on the pull-up on the ADDR pin, I believe the 7-bit address should be 0x2D, giving a write address of 0x5A and a read address of 0x5B. Could you confirm if that looks correct?

To be sure, I tried both 7-bit addresses 0x2c and 0x2d.

Here is the result of my i2cdetect:

root@evk-kit-ai:~# i2cdetect -y -r 2
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- UU -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: UU -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- UU 69 -- -- -- -- -- UU
70: -- -- -- -- -- -- -- --

I also tested with i2ctransfer:

root@evk-kit-ai:~# i2ctransfer -y -f 2 r1@0x2d
Error: Sending messages failed: No such device or address

root@evk-kit-ai:~# i2ctransfer -y -f 2 r1@0x2c
Error: Sending messages failed: No such device or address

As you can see, using both 8-bit read addresses (0x5B and 0x59) does not return an ACK on the 9th bit.

To confirm further, I tried write transactions on both addresses, and here are the results:

root@evk-kit-ai:~# i2ctransfer -y 2 w1@0x2d 0x0d r1@0x2d
Error: Sending messages failed: No such device or address

root@evk-kit-ai:~# i2ctransfer -y 2 w1@0x2c 0x0d r1@0x2c
Error: Sending messages failed: No such device or address

Again, using the 8-bit addresses (0x5A and 0x58) I don’t get an ACK.

Despite testing both the 7-bit and 8-bit addresses with i2cdetect and i2ctransfer, I consistently receive 'No such device or address' errors and no ACK. Could you advise on what I might be missing or suggest the next steps to debug this?

Thank you for the support,

Gabriele

Hi Gabriele,

Have you checked this on multiple boards and do they all show the same behavior?

Could you also please control the EN pin and make sure it is enabled after the power rails are stable.

If possible, if you have another I2C-capable device available, could you wire and/or solder on the I2C lines and check if it can detect the device?

Best regards,
Ikram

Hi Ikram,

I tested all 5 of my prototypes and observed the same behavior on each of them. Regarding the EN pin, I verified it by removing the pull-up resistor, shorting it to GND, and then releasing it while the board was already powered on. The behavior remained unchanged.

Unfortunately, I don’t have another I2C-capable device available to connect to the bus. What I find puzzling is that I can successfully communicate with all the other devices on the I2C lines, but not with this one.

Thank you very much for your support.

Best regards,

Gabriele Vezzali

Hi Gabriele,

Could you probe the I2C pins close to the device and check the signals. Please also check the layout for this, the I2C traces and connections, device footprint, and power rails.

The I2C speed here is 100 kHz right? This is within the 400 kHz limit as well. Since this is seen on all the prototypes, and there is no known issue with I2C like this, there could be a system issue, with the layout and connections. 

Best regards,
Ikram

Hi Ikram,

The i2c speed is indeed 100 kHz, and the layout of the board seems good to me.

This is a probe done as close as i can on the pin of the i2c (yellow=sda pink=scl).

regards,

gabriele vezzali

Hello,

The team is out due to a public Holiday in the US. Responses will be delayed until Monday.

Thank you for your patience

Hi Gabriele,

Thank you for sharing these. I could not yet identify the cause for this since the pinout compared to the layout looks correct. Is the part soldered on correctly? Is it possible that it was rotated somehow?

Hi Ikram,

We identified a hardware error on our side. To continue testing, we have purchased an EVM board for now.

Thank you for your support.

Best regards,

Gabriele