Summary of some problems in sensor bring up

1、 background ：

Generally, we are debugging a sensor The effect of , First, light him up , Also called sensor bringup, This part of the work is mostly completed by the drive engineer , But sometimes it is necessary tuning The engineer did it , But in fact, if it goes smoothly , stay sensor Configured in the driver sensor setting,、i2c Address 、sensor Of chip_id, Then you can plot , But most of the time , It doesn't always go so well , There will be many problems , Here's a summary , Whole sensor bringup The process of , And some of the problems ;

2、Sensor bringup technological process ：

• towards sensor The specification required by the original factory application Sensor setting, Such as resolution 、 Platform Mclk、 Frame rate 、 Output raw Bitwidth of graph 、mipi_lane Count , If necessary, the maximum supported by the platform shall not be exceeded mipi rate ;
• Get setting after , Conduct sensor Drive configuration , First, configure sensor setting、I2C Address 、chip_id;
• Get the schematic diagram of the motherboard , Confirm the hardware related configuration , According to the schematic diagram of the motherboard, the dts Middle configuration mclk、reset、pwrdn、i2c Pin control ;
• After the above steps are completed , If the hardware is OK , Basically, you can light up the map , And then according to sensor datasheet, Detailed configuration sensor The exposure time of , Analog gain and other registers are OK  ;

3、 The problem summary ：

a、 How to determine reset、pwrdn、i2c、mclk The pin of ？

First, learn to read the schematic diagram , I was very confused when I got the picture at first , There are too many things in a mess , I don't know where to start , In fact, there are not many places to pay attention to , You don't need to understand the whole picture , Because we mainly configure camera, So we found MIPI_CSI Interface part , Here's the picture a, Focus on the CM_RST_L (reset)、CM_PWRDN (pwrdn)、CM_I2C_SCL(i2c_clk)、CM_I2C_SDA( i2c_data )、CM_MCLK (mclk) Just a few control pins , With mclk For example , Let's find the picture first a Of mipi_csi Part of the CM_MCLK ——> chart b MCLK_0 ——> chart c Of MCLK_0——> Master GPIOA_0 , In fact, it is to look up in turn , Up to the main control pin .

b、I2C no ？

• i2c Wrong address ： commonly i2c There are two addresses , It is different to pull the level up and down , As shown below sc4335p Of I2C Address description , And the following address is 7bit Address , The default configuration of the general drive is 8bit Address , Therefore, it is necessary to move to the left when configuring the driver 1 position , become 0x60.
• Check out the hardware The problem with the power supply AVDD,DVDD,IOVDD, The three power supplies of some hardware are normally powered , Some three power supplies are controlled by software If it is controlled by software , The control pins of these three power supplies need to be added to the driver .
•  mclk Incorrect pin configuration ： It can be provided to with oscilloscope sensor Does your clock have , Or whether the clock is right , Such as :24MHz、27MHz.
• i2c Incorrect pin configuration ： Generally, you can view the corresponding information of the master controller pinmux-pins file , Confirm the corresponding GPIO Has it been defined correctly ;
•  reset、pwrdn Incorrect pin control ： First dts Configure the corresponding reset、pwrdn The pin of , next sensor Drive to control the pull down 、 pull up , According to sensor datasheet To confirm , The following is ov02k10 Sequence diagram , Only reset Pull up operation , That's all right. , No, pwrdn The operation of ;

 c、 No drawing or abnormal drawing ;

• ISP Input the order here and check mipi Whether the transmission of err.
• You can measure with an oscilloscope mipi The signal .
• Catch raw See if there is any abnormality , If raw There are also exceptions in the figure, which are generally sensor setting The problem of , look for sensor People from the original factory went to see .
• There are vertical stripes after increasing the gain （ Also called FPN）, and sensor relevant , General sensor Original treatment ;

•   There are horizontal stripes under low illumination , Generally related to hardware , Power supply noise or device interference ;