I've tried AQM1602 16x2 character LCD

I bought character LCD with I2C interface. LCD itself costs 450 yen. I soldered the LCD to 2.54mm pitch pin header. I put resistors and condensers on the bread board.

I connected the LCD into Raspberry Pi2's 3.3V, GND, and SDA signals. I didn't put pull-up resistors because those signals are pulled-up internally by Raspberry Pi 2.

I2C address of the LCD is 0x3E. "i2cdetect" command returns 0x3E correctly.

LCD shows characters by sending commands via I2C according to initialize steps written in the usage manual of the LCD. Sometimes commands failed, but they succeeds if I put long wait time. I found that the command fails if the I2C baud rate is 100000 of default value. If I change it by 50000, command succeeds stably. We can change the baud rate by writing the following lines into /boot/config.txt:

dtparam=i2c_baudrate=50000