DRA829VXEVM: Connecting AR0820 sensor to CSI2 expansion connector using native interface

Matan,

Can you please clarify - which signal are you inquiring about?

Regards,

Mayank

Hi Maynak,

CSI2_RSTz_DV

Thanks,

Matan

Matan,

I am copying Vivek, our CSI2 expert to answer this. If CSI2 module is not coming out of reset, here are a few things you should check:

1. CSI2 clock is being generated and is clean

2. All the lane assignments and polarities are correct

3. Sensor does not start streaming till it receives the STREAMON message from the application. For AR0820 this would mean the bit 'RESET_REGISTER_STREAM' in the sensor register 0x301c

Hi Mayank, Vivek,

1. CSI2 clock is generated OK by on board oscillator (not driven by the EVM)

2. Verified

3. It seems that the sensor doesn't return to I2C commands.

I used the same driver for the AR0820_LI, relying on the fact that configuring the SERDES (953 & 960) will not change in the functional level.

Thanks,

Matan

[MCU2_1]    659.225670 s: [MHD] chipIdRegValueRead=0xabcd ; AR0820_CHIP_ID_REG_VAL=0x557 ; count=0 ; max_retries=5
[MCU2_1]    659.225711 s: [MHD] Now will read register - i2cInstId=0x6 ; sensorI2cAddr=0x10 ; chipIdRegAddr==0x3000 ; chipIdRegValueRead=0xa3a73f10 ; 1U
[MCU2_1]    659.225763 s: [MHD] Sensor I2C Handle is NOT NULL
[MCU2_1]    659.225786 s: [MHD] Calling Board_i2c16BitRegRd -  sensorI2cHandle=0xa393a690 ; i2cAddr=0x10 ; regAddr=0x3000 ; &readReg8_High=0xa3a73ee4 ; 1U ; sensorI2cByteOrder=0x1 ; I2C_WAIT_FOREVER=0x0

If the sensor is not responding to I2C, I would suggest you to check the following:

1. Sensor is getting the power.

2. I2C instance is correct. TI driver uses i2cInstId=0x6 as per EVM design, but on your board it could be different.

3. I2C address (0x10) is correct for your camera module.

1. The sensor is getting power (measured the required voltages)

2. I suspect something is wrong with the RESET signal. It comes from IO Expander - where is it configured?

I2C is not controlled by CSI2_RESET. Let's first get I2C working and get the sensor in streaming mode.

I was referring to CSI2_RSTz_DV that is stuck in LOW

CSI2_RSTz_DV does not control I2C

Yes, I know. But signal is the reset signal for the sensor.

For some reason this signal is held in LOW so I would guess this is the reason for the I2C to fail

Hi Maynak,

I've been looking into the schematics of the fusion board. It seems that Pin14 in the CSI2 extension connector which should be the reset_n signal for the sensor isn't connected in the fusion board.

Hence, I would guess that the reset_n signal to the sensor is configured by the 960/953 on the fusion board.

So when I'm connecting a sensor module via its native interface directly to J52, I need to update the driver to drive this reset_n signal.

My question is how do I do it? Can you please explain how to configure the I/O expander to drive this signal?

Are there any additional updates I should apply to the original driver?

Thanks,

Matan

Hello Matan,

This signal is connected through I2C expander, TCA6408.  Address is 0x20, bit P0.  Pulled low to default to ‘0’ or reset asserted.

Regards,

Mayank

Hi Mayank,

I couldn't find in the source code the location in which this signal is asserted/de-asserted. Can you please point me in the right direction?

Moreover, if this signal isn't currently driven by the driver but relies on the PD resistor and 953 operation, I can connect this reset_n signal to VCC_IO on my module and getting the sensor out of reset, rather than handling the I/O expander configuration.

Are there any additional updates I should apply to the original driver?

Thanks,

Matan

Hello Matan,

All the current drivers are FPD link coming through Fusion1 board which does not use CSI2_RESET signal This is why you don't find it being toggled in the code. You will need to write code to set pin0 of TCA6408 to assert reset.

Regards,

Mayank

Hi Mayank,

OK. As it's not being toggled by the current code, I forced it to VCC_IO on my module, hence overcoming the PD.

It still doesn't work and the I2C command is failed.

Are there any additional updates I should apply to the original driver?

Thanks,

Matan

Hello Matan,

I am not familiar with design and interface of your module, so I am not able to comment on driver changes required. Please try the IO expander setting as mentioned in the last post. If that does not work I would suggest doing a schematic review of your camera board.

Regards,

Mayank

Hi Mayank,

I'm trying to add the code to configure the IO expander.

However, when including the 'board_i2c_io_exp.h" file in the driver, I get that some files are missing...

xdc/std.h

ti/csl/src/ip/uart/V0/cslr_uart.h

Both header files are indluced in the tistdtypes.h file.

All I need is just the functions which set the IO expander pins.

Thanks,

Matan

Hello Matan,

If you are doing it from image sensor code, you can access TCA6408 device as follows:

    uint32_t tca6408I2CSlaveAddr = 0x20;
    uint8_t regAddr = 0x3;
    uint8_t regVal = 0xFE;

    status = Board_i2c8BitRegWr(gISS_Sensor_I2cHandle, tca6408I2CSlaveAddr, regAddr, &regVal, 1U, SENSOR_I2C_TIMEOUT);

You will need to change regAddr and regValue as per your needs. You can find TCA6408 datasheet at 

http://www.ti.com/product/TCA6408A

Regards,

Mayank

Hi Mayank,

I managed to configure the IO expander and now I can stream data from the sensor. However, I can't see image on the DP screen.

I saw that the configured resolution is 4K @ 27 fps (the original sensor configuration).

What could be the reason that I can't see the video on the screen? Does the 953/960 decreases the resolution in the demo code?

Thanks,

Matan