Documentation and explanation of example code

[kurisutofu]

Hi,

I’m playing with the motorized focus camera and used the example code from your github.
While it is working fine, I’m having a hard time understanding what it is doing.

I’m talking about the following code:

value = (temp_val<<4) & 0x3ff0
dat1 = (value>>8)&0x3f
dat2 = value & 0xf0
os.system("i2cset -y 0 0x0c %d %d" % (dat1,dat2))

1 – I understand it’s using bitwise operators but what is it calculating?
What is the purpose for dat1 and dat2?

2 – Is there any doc I can refer to?
For example, the chip and data address, are they fixed? Is it always 0 and 0x0c?

3 – What are the SCL and SDA pins for?

4 – What are the min/max values for dat1 and dat2?

Thank you.

• This topic was modified 7 months ago by kurisutofu.

[bin]

Hi,
1 – I understand it’s using bitwise operators but what is it calculating?
What is the purpose for dat1 and dat2?

This value is used to driver the motor current, Output current = (D[9:0]/1023) X 120mA
User can control the motor rotate different angles through changing different current.
the data1 is the value of D9-D4 and the data2 is the value of D0-D3.

2 – Is there any doc I can refer to?
For example, the chip and data address, are they fixed? Is it always 0 and 0x0c?
The chip address is 0x0C, for the detail information, please refer to https://www.arducam.com/downloads/DW9714A-DONGWOON(Autofocus_motor_manual).pdf
3 – What are the SCL and SDA pins for?
This signal is i2c bus and used to control the motor

4 – What are the min/max values for dat1 and dat2?
The value range of the dat1 is 0x00 – 0x3F. The value of the dat2 is 0x00-0x0F.

[kurisutofu]

Hi bin lv, thanks for the reply, it’s very useful!

I’m not sure I understand what D[0:9] are but I’ll look into it.

[bin]

OK. Let me know if you need more help.

[Author]

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