Difference between revisions of "I2c bus"
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| + | = Wiring - Raspberry = | ||
| + | <pre> | ||
| + | Color i2cbus Raspberry Pi | ||
| + | yellow SCL GPIO 3 / SCL (Pin 5) | ||
| + | orange SDA GPIO 2 / SDA (Pin 3) | ||
| + | Red VCC / V 3,3V (pin 1) | ||
| + | Black GND GND (Pin 6) | ||
| + | </pre> | ||
| + | = Software - Raspberry = | ||
| + | Example with both a {{Link|target=SSD1306}} and {{Link|target=PCA9685}} on the bus | ||
| + | <source lang='bash' highlight='1,3'> | ||
| + | sudo raspi-config | ||
| + | # enable i2c in Interfacing options | ||
| + | sudo i2cdetect -y 1 | ||
| + | 0 1 2 3 4 5 6 7 8 9 a b c d e f | ||
| + | 00: -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- -- | ||
| + | 40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- | ||
| + | 70: 70 -- -- -- -- -- -- -- | ||
| + | </source> | ||
| + | |||
| + | = How many devices on the bus? = | ||
https://www.bluedot.space/tutorials/how-many-devices-can-you-connect-on-i2c-bus/ | https://www.bluedot.space/tutorials/how-many-devices-can-you-connect-on-i2c-bus/ | ||
= Pull up resistor calculation = | = Pull up resistor calculation = | ||
| + | It seems recommendations go from 1kΩ (maximize speed) to 10kΩ (minimize power consumption) 4.7 kΩ is a compromise | ||
== Stackoverflow == | == Stackoverflow == | ||
* https://electronics.stackexchange.com/questions/1849/is-there-a-correct-resistance-value-for-i2c-pull-up-resistors | * https://electronics.stackexchange.com/questions/1849/is-there-a-correct-resistance-value-for-i2c-pull-up-resistors | ||
| + | Most upvoted answer: | ||
| + | ''I include 4K7 resistors in the kit which seems like a reasonable compromise for most users.'' | ||
== Ti.com == | == Ti.com == | ||
Latest revision as of 10:20, 7 February 2020
Wiring - Raspberry
Color i2cbus Raspberry Pi yellow SCL GPIO 3 / SCL (Pin 5) orange SDA GPIO 2 / SDA (Pin 3) Red VCC / V 3,3V (pin 1) Black GND GND (Pin 6)
Software - Raspberry
Example with both a SSD1306 and PCA9685 on the bus
sudo raspi-config
# enable i2c in Interfacing options
sudo i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --
How many devices on the bus?
https://www.bluedot.space/tutorials/how-many-devices-can-you-connect-on-i2c-bus/
Pull up resistor calculation
It seems recommendations go from 1kΩ (maximize speed) to 10kΩ (minimize power consumption) 4.7 kΩ is a compromise
Stackoverflow
Most upvoted answer: I include 4K7 resistors in the kit which seems like a reasonable compromise for most users.
Ti.com
Therefore,we can selectany available resistor value between 966.667Ωand 1.77kΩ. The valueof the pull up resistor can be selected basedon the trade-off for the power consumption and speed.