I have a Raspberry Pi 4B and I'm trying to hook it up with a 4x20 character LCD using a PCF8574T-based I2C interface. The interface operates at 5V so I'm also using a logic level converter. It would be difficult to make decipherable photos of the circuit, so I made a figure:
In case the labels get lost, for the I2C the pins go like this:
GND, VCC, SDA, SCL
For the LLC, the high voltage side is on the left, low voltage on the right.
I installed python-smbus and i2c-tools, I have I2C interfacing enabled, I added i2c-bcm2708 and i2c-dev to
/etc/modules, I don't have anything blacklisted.
lsmod | grep i2c yields the following:
i2c_bcm2835 16384 0 i2c_dev 20480 0 i2c_bcm2708 16384 0
/boot/config.txt I added these lines:
Still, when I run
i2cdetect -y 1 I get an empty table with no devices detected.
I tried rebuilding the circuit multiple times, I tried a different breadboard, I tried skipping the breadboard altogether, but I still can't get the I2C to work.
Here's an Imgur album of the circuit, sorry about the quality: link
Is there anything I'm missing?
Thanks in advance!