SN65DSI86: SN65DSI86ZQER i2c communication not working

Hi,

I do not see an issue with your schematic. 

Do you have a way to isolate the other devices from the I2C bus and just leave the DSI86 on the I2C bus? 

If you are reading the DSI86 Registers 0x00 to 0x08, are you able to see on the scope that the host is issuing the read request to the DSI86?

Thanks

David

Hi Thakor,

Can you please put scope probe on I2C lanes and capture I2C read or write transaction to the device?

Regards,, Nasser

Hello David,

Thanks for reply

Here only DSI86 is connected with host mcu and using that i'm trying to read address of DSI86 but it's not detecting address.

once it detect then i make sure that communication is working and i can go ahead with configuration.

Hello Nasser,

Thanks for reply

Yes i will do that will update you for the same.

Hi, Thakor

I would double check the DSI86 power up sequence and make sure the DSI86 is being reset properly. 

Have you tried to change the pullup resistor value on the SCL and SDA to see if it makes a difference?

I would then follow Nasser's suggestion and physically probe the I2C bus during the read operation of the DSI86 registers 0x00 to 0x08.

Thanks
David

Hello David,

I'm not aware of power up sequance.

and also en pin is grounded with capacitor.

do i need to pull up EN pin?

hi,

it seems to me that sda scl working fine because i noticed pulse burst on scl sda pins using DSO

Hi,

EN pin already has an internal pullup so there is no need for an external pullup. You only need an external pulldown capacitor on the OE pin to passively reset the DSI86. Typically we recommend a 0.22uF capacitor on the OE pin to ensure sufficient power up reset timing.

Can you decode the I2C bus to verify there is a register 0x00 read request to address 0x2C?

Thanks

David

Hi,David

there is no OE pin with DSI86 chip

are you mean EN pin?

and i have already placed 200nF(0.22uF) across EN pin and GND.

still no i2c detection,so please help

Thanks

Hi,

OE is a typo on my part, it should be the EN pin.

Did you get a chance to decode the I2C traffic and verify the source is sending the read request to address 0x2C? The DSI86 is a I2C secondary and will only respond if the address is correct. 

Have you also tried to change the pullup resistor on the I2C SDA and SCL and see if that makes a difference?

Thanks
David

Hello David,

Yes i have already checked and it's sending 0x2C address.

and i have tested this code with other i2c sensor and it's detecting

so may be it's DSI86 board side issue.

and i also tried with 2.7K resistor instead 4.7K still same issue.

Thanks

Hi,

The registers 0x00 to 0x08 are read-only registers. If the DSI86 is not being hold in reset and the I2C read command is correct, the DSI86 will return the correct data in the registers 0x00 to 0x08.

Does this issue happen on multiple DSI86 boards? Do you have an EVM that you can test with your I2C host controller?

Thanks

David

Hi david,

sorry for late reply,

i will check it .

and i don't have evm board.

currently i'm trying to solve it anyhow.

i will update you soon.

thanks