i2c interface module w/ 16×2 lcd connected to pi zero

Lcd illuminates but no text is being displayed. On the back of the i2c interface module I turned the screw in both directions, however the contrast was not adjusted. The screw is now stripped. Would it be possible to add a potentiometer to control the brightness?

configuration:

pi@raspberrypi:~ $ uname -a
Linux raspberrypi 4.4.27+ #2 armv6l GNU/Linux

pi@raspberrypi:~ $ i2cdetect -l
i2c-1 i2c       20804000.i2c  I2C adapter

i2cdetect01.png
raspi-gpio01.png

raspi-gpio02.png

raspi-gpio03.png
pi@raspberrypi:~ $ vcgencmd version
Copyright (c) 2012 Broadcom
version faf071dd4885c5ac1a89483d35a5326e7f69495f (clean) (release)

gpio_readall.png
installed python-smbus and i2c-tools

enabled i2c in raspi-config
raspi-config.png
lsmod.png

config.txt.png

hardware setup:

lcd_backplate.JPG

lcd_closeup.JPG

lcd_bright.jpg
lcd_back.JPG

pinout
pinout.png

any suggestions on what else to troubleshoot?

i2c interface module w/ 16×2 lcd connected to pi zero

raspberry pi usb/serial connect 💻

I am having dificulty installing a Micro SATA cable usb 2.0 TTL UART 6pin module serial converter CP2102 and USB to RS232/TTL PL2303HX cable adapter COM module auto converter on a Macbook Pro early 2011 with Yosemite 10.10.3

Prolific_resized SLAB_resized

I ran the following command within the Terminal window

kextstat | grep prolific
148 0 0xffffff7f82bb0000 0x7000 0x7000 com.prolific.driver.PL2303 (1.5.1)

ioreg -c IOSerialBSDClient | grep usb
| | | “IOTTYBaseName” = “usbserial”
| | | “IOCalloutDevice” = “/dev/cu.usbserial”
| | | “IODialinDevice” = “/dev/tty.usbserial”
| | | “IOTTYDevice” = “usbserial”

ls /dev/tty.*
/dev/tty.Bluetooth-Incoming-Port
/dev/tty.Bluetooth-Modem
/dev/tty.usbserial

system_profiler SPUSBDataType
USB-Serial Controller:

Product ID: 0x2303
Vendor ID: 0x067b (Prolific Technology, Inc.)
Version: 3.00
Speed: Up to 12 Mb/sec
Manufacturer: Prolific Technology Inc.
Location ID: 0xfa130000 / 6
Current Available (mA): 500
Current Required (mA): 100

network01 usb_information_prolific network02

usb_information

system_profiler SPUSBDataType
CP2102 USB to UART Bridge Controller:

Product ID: 0xea60
Vendor ID: 0x10c4 (Silicon Laboratories, Inc.)
Version: 1.00
Serial Number: 0001
Speed: Up to 12 Mb/sec
Manufacturer: Silicon Labs
Location ID: 0xfa130000 / 6
Current Available (mA): 500
Current Required (mA): 100

ls /dev/tty.*
/dev/tty.Bluetooth-Incoming-Port
/dev/tty.Bluetooth-Modem
/dev/tty.SLAB_USBtoUART

when I type screen /dev/tty.usbserial 115200 8N1 or screen /dev/tty.SLAB_USBtoUART 115200 8N1 I just get a blank screen with a blinking prompt. I am not able to type anything, it appears to be hung.

These are the gpio settings that I used. I tried applying the 5v pin and without. When the 5v pin was not connect, I used the regular charger to supply power.

rasp_pin_layout

raspberry pi usb/serial connect 💻