OPT3101: OPT3101. Problems programming memory register via I2C

Do you know if there is another version of this IC. Could be possible that a internal change has been done? Thanks in advance.

Hi,

There is no internal change on the IC. Are you seeing this on multiple OPT3101 units or only one? You are communicating directly with the IC over I2C on the EVM (MSP on evm not used)? What other differences are there between the EVM and your custom board? Which register are you reading? I assume you are writing a value and reading back expecting to see the written value and instead seeing the default value?

Best,

Alex

Thanks Alex in advance. 

The differences between my custom board and the EVM are few. Basically I have isolated the ToF sensor. The microcontroller is is another board. I attach the sck.

I am trying to write a lot of registers: 89h, 6Eh, 80h.... but the result is always the same. I am pretty sure that electrically the board is working fine. It is a very strange failure. 

I am thinking that maybe there is some new initialization sequence ( HW reset + firmware reset, i do not know). Now i wake up the IC via HW reset, waiting 2 ms with RST line at 0 volts and then put it to 5 V. Also, I wait 5 seconsd to start to send I2C commands.

Regards.

Can you share a scope capture on the i2c lines close to the OPT3101 during this process?

Best,

Alex

Thanks in advance Alex. Here you can see three differents captures: the first is a reading frame, the second is a writting frame and the last is reading frame close up.

As you can see the signal integrity is very good. 

Other thing that i forgot, sometimes when I am debugging my driver can see that some writtings are good. I have tried to insert some delays between writings but the result is the same. 

Regards.

Thanks, will check this. Also can you confirm on my other question: Are you seeing this on multiple OPT3101 units or only one?

Hi Alex, we have ordered 5 units of this board to check it and all of them have the same issue. Could be a bad fabrication batch?  

Hi,

I will send this to our quality team to get their thoughts and let you know. I also see in the i2c that there are some glitches on the data line. Are you sure these are not from the scope/setup related or from the master? 

Also are you able to do a swap on the EVM board and solder the EVM IC to your board and put this failing unit on the EVM and check both? That would help in isolated problem to the device. Do you have any known good OPT3101 ICs you have previously been able to verify working in the setup?

Best,

Alex

Yes I see the glitches but i think that it shall not affect because there are on the falling edge of the clock signal. Also, I am able to control de EVM´s OPT3101 (after remove the MCU)  from my driver without any problem. 

Actually, I can communicate with my board at 50 kHz but not at 100 kHz and 400 kHz. These is a problem if I want to use the EVM as a calibration driver because the EVM´s I2C driver is working at 400 kHz.

I will try to change the OPT3101 IC and give you feedback. Firstly, I am going to try to use another I2C driver to see if the behaviour is the same.

Regards.

Hi,

To confirm, removing OPT3101 IC from the EVM board and putting on your board works but only at 50kHz and not 100kHz or 400kHz? What is the issue at these higher speeds?

Best,

Alex

Thanks Alex, i am going to change the IC during today. I will inform you with the results. As news I can tell you that i have tried another PCB and now all is working fine. I think my suspicions were true and there is some problem with some ICs. 

Thanks in advance.