The CAP1188 has a lot going on, so much so that we had to make the breakout double-sided! It fits nicely into a breadboard and has the sensors all in a row on one side and if you're using plain i2c you can connect to to the left side only
Here's all the pins and what they do!

Power pins

VIN and GND are power in pins, you can use 3-5VDC so its great for any kind of microcontrollers. There's an on-board 3V regulator as well, the output is available on the 3Vo pin (you can snag up to 150mA)

I2C interface pins

For I2C, connect to the SCK (i2c clock a.k.a SCL) and SDA (i2c data) pins. These are 5V safe so you can use them with 3V or 5V logic

SPI inteface pins

If you want to use SPI instead, you'll be using the SCK, MOSI, MISO and CS pins

Other interfacing pins

The AD pin is used to select SPI or I2C interface, and if I2C what address to use. See the wiring page for more details
The IRQ pin goes low when a pin is touched. We don't use it on our code examples, but if you want to have an interrupt pin used, connect it to this IRQ pin and use active-low triggering.
The RST pin is used to reset the chip, either in I2C or SPI mode. It's optional but using it will make the system more reliable so we suggest it.

Sensor input pins

This is the part you touch - there are 8 individual capacitive sensor pins, called C1 thru C8. On restart the system recalibrates them so don't touch these when powering up!

Sensor output pins

The L1 thru L8 pins are the LED driver/sensor output pins. The indicators are really useful for debugging your touch sensor system, but you can also use the indicator output pins for triggering some other electronics. Each L pin corresponds to the matching C sensor input. These pins are 3V normally, and drop to 0V when triggered.

This guide was first published on Jan 10, 2014. It was last updated on Jul 13, 2024.

This page (Pinouts) was last updated on Jan 10, 2014.

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