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USB superspeed peripherals Forum Discussions

MaHe_4626536
Level 1
Level 1

Hi,

As the CX3 supports Multi-Master mode of I2C, it's possible to connect another I2C master on the same bus (CX3-Sensor).

I would like to send direct I2C commands from Aardvark, for example, to the sensor for configuration.

What will be the best option?

1. Use the multi-master mode option and just connect another master. Are there any required configuration in the CX3 to support it?

2. Mux the I2C signals to the sensor?

Thanks,

Matan

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1 Solution

EDITTED for Clarity.

Hello,

We are not recommending customer's to use CX3 I2C interface in multi-master configuration. We have seen some failures in the past (when used in multi master system) and there by recommend to use I2C interface in single master mode. Please refer to Errata 6 (Page 33) of CX3 datasheet to understand the possible failure while using Multi Master mode of I2C. The link to the datasheet is given below:

https://www.cypress.com/file/133591/download

Please let me know what exactly do you mean by "sensor". Is it the image sensor that sends out the data over the MIPI interface of CX3?

If this is the case, then you can use the I2C interface of CX3 itself for configuring the image sensor.

Note: If you are using an external master for configuring the image sensor, then the image sensor should be configured only after the MIPI block of CX3 is configured. The configuration of MIPI block is done by CX3's I2C Master. When a SET_CUR request comes from the host, firstly the MIPI block should be configured for that particular resolution/format. The image sensor should be configured for that resolution/format only after the MIPI block is configured. You need to handle this correctly so that the streaming is not affected.

Best Regards,

Jayakrishna

Best Regards,
Jayakrishna

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5 Replies
JayakrishnaT_76
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hello,

We are not recommending customer's to use CX3 I2C interface in multi-master configuration. We have seen some failures in the past (when used in multi master system) and there by recommend to use I2C interface in single master mode. Please refer to Errata 6 (Page 33) of CX3 datasheet to understand the possible failure while using Multi Master mode of I2C. The link to the datasheet is given below:

https://www.cypress.com/file/133591/download

Best Regards,

Jayakrishna

Best Regards,
Jayakrishna
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Hi Jayakrishna,

Thanks for the your answer.

Can you please confirm that there is no problem in connecting directly to the I2C of the sensor, bypassing the I2C bus from the CX3 to the sensor?

Thanks,

Matan

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EDITTED for Clarity.

Hello,

We are not recommending customer's to use CX3 I2C interface in multi-master configuration. We have seen some failures in the past (when used in multi master system) and there by recommend to use I2C interface in single master mode. Please refer to Errata 6 (Page 33) of CX3 datasheet to understand the possible failure while using Multi Master mode of I2C. The link to the datasheet is given below:

https://www.cypress.com/file/133591/download

Please let me know what exactly do you mean by "sensor". Is it the image sensor that sends out the data over the MIPI interface of CX3?

If this is the case, then you can use the I2C interface of CX3 itself for configuring the image sensor.

Note: If you are using an external master for configuring the image sensor, then the image sensor should be configured only after the MIPI block of CX3 is configured. The configuration of MIPI block is done by CX3's I2C Master. When a SET_CUR request comes from the host, firstly the MIPI block should be configured for that particular resolution/format. The image sensor should be configured for that resolution/format only after the MIPI block is configured. You need to handle this correctly so that the streaming is not affected.

Best Regards,

Jayakrishna

Best Regards,
Jayakrishna
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Hi Jayakrishna,

Yes, I was referring to the image sensor.

Naturally, all the configuration will be performed by the CX3. However, I would like to add an option to configure the image sensor via its I2C interface, regardless of the CX3, for debug and testing.

Thanks,

Matan

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Hello,

Please let me know if you have more queries on this.

Best Regards,

Jayakrishna

Best Regards,
Jayakrishna
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