I just created a driver for NuttX to use JLX1602G-390 display.
This display is based on Siatronix ST7032i the I2C version.
First you need to wire it connecting an external capacitor and a resistor as explained on this schematic:
I am using the STM32F4Discovery board with this display connecting pins PB6 to SCL and PB9 to SDA. These pins are configured to enable an internal pull-up resistor, but case your microcontroller doesn’t have it, you need to connect external pull-up 4k7 resistors to SCL and SDA pins.
After configuring the NuttX to use this display, you can execute the slcd command from NuttShell:
Opening /dev/disp0 for read/write access
rows: 2 columns: 16 nbars: 0
max contrast: 0 max brightness: 1
0000: 1b5b46 .[F
Set brightness to 1
Print [Hello World NuttX]
0000: 48656c6c6f20576f726c64204e757474 58 Hello World Nutt X
After implementing the MLX90614 driver for NuttX I noticed that although the write command to change the device I2C address in the EEPROM was reporting success, after the power cycle the new address was not working. Worst: even the previous address was not working.
Basically the device appears damaged and didn’t respond to any I2C command.
Then doing my research I discovered a Melexis document about SMBus communication:
In this document I noticed they are using the address 0x00 instead of the default 0x5a address. After modifying the driver to use the 0x00 address the device accepted the new command.
There are many discussing about this subject on Arduino and similar forum: