Using (2) I2C accessories: LCD & MPR121 Capacitive Touch Sensor Board

[TonyAme]

Thank you. I'm planning to use two I2C accessories; an LCD and the Adafruit MPR121 Capacitive touch sensor board. Should I use separate I2C pins (SCL, SDA) on the Teensy 4.0? (i.e., SCL0, SDA0 for the LCD, and SCL1, SDA1 for the MPR121 cap touch board?)
I'm also planning to use the Teensy Audio Adapter board for the Teensy 4.0

Thank you for any info.
TonyA

Update: All seems to be working connected to the same I2C lines; SCL0, SDA0. Thank you.

 

[MichaelMeissner]

Thank you. I'm planning to use two I2C accessories; an LCD and the Adafruit MPR121 Capacitive touch sensor board. Should I use separate I2C pins (SCL, SDA) on the Teensy 4.0? (i.e., SCL0, SDA0 for the LCD, and SCL1, SDA1 for the MPR121 cap touch board?)
I'm also planning to use the Teensy Audio Adapter board for the Teensy 4.0

Thank you for any info.
TonyA

Update: All seems to be working connected to the same I2C lines; SCL0, SDA0. Thank you.

Generally as long as the I2C addresses are different, things should work. I2C is designed to be a shared bus so the master processor can talk multiple difference devices.

I've read there are some corner cases where things might not work, but I believe they are fairly rare:

• Having multiple devices can mean the total length of the I2C bus gets to the point where things electrically don't work.
• IIRC, I2C has different speeds that the master/slave host can communicate at, and there may be some issues if you have different devices running at different speeds.
• Most I2C devices these days have pull-up resistors to make the I2C communication work. These pull-up resistors are cumulative, and as you have more resistors on the bus, it means you might not be able to communicate at highest speeds. And I imagine in the worse case, I2C won't work.

 

[TonyAme]

Generally as long as the I2C addresses are different, things should work. I2C is designed to be a shared bus so the master processor can talk multiple difference devices.

I've read there are some corner cases where things might not work, but I believe they are fairly rare:

• Having multiple devices can mean the total length of the I2C bus gets to the point where things electrically don't work.
• IIRC, I2C has different speeds that the master/slave host can communicate at, and there may be some issues if you have different devices running at different speeds.
• Most I2C devices these days have pull-up resistors to make the I2C communication work. These pull-up resistors are cumulative, and as you have more resistors on the bus, it means you might not be able to communicate at highest speeds. And I imagine in the worse case, IC won't work.

Thank you. I hooked everything up and all is good. Thank you for the info you included here, I appreciate this!