NeXT Pi

November 23, 2018 | #raspberrypi #3dprint

NeXT Computer (also called the NeXT Computer System) is a workstation computer that was developed marketed, and sold by NeXT Inc. This is a write-up of a maker project to replicate the original NeXT computer (plus some mods) with a Raspberry Pi.

A NeXT Computer and its object oriented development tools and libraries were used by Tim Berners-Lee and Robert Cailliau at CERN to develop the world’s first web server software, CERN httpd, and also used to write the first web browser, WorldWideWeb. – from Wikipedia

This project is based on a previous and very similar one by Nina Richards. I will not focus on the 3D parts since they are well described on the mentioned blog post by Nina Richards.

Parts

Parts overview Image credits to Nina Richards.

3D Parts

Count Part
1 Front/Body
1 Front Panel (Grid)
1 Tray
6 Fins with spacers
1 Fin
1 Back Section

All the 3D model STLs are available on Thingiverse. The mod of having the 16x2 LCD required drilling a hole on the Front/Body part, the new STL will be shared eventually.

Other Parts

Count Part
1 Raspberry Pi 2 (compatible with version 3)
2 3mm LEDs (or similar)
3 Female header connectors
2 82Ω Resistors
1 Power Switch
1 Panel Mount micro-USB socket
1 micro-USB cable
1 Panel Mount HDMI socket
4 5mm heat-set brass threaded inserts with M3 thread
4 M3 6mm countersunk screws
4 3mm x 4mm self-tapping screws
4-8 Heat-shrink tubes
1 16x2 LCD with I2C

All the parts were brought in Aliexpress. You can easily find similar ones on eBay, Amazon or any other hardware parts seller.


Mount Instructions

Wiring Diagram

Raspberry Pi 2 Schematic

Raspberry Pi 2

Fritzing Wiring Diagram

Circuit

Fritzing Schematic Download

Changing the Activity LED default GPIO

To change the status LED from the default on-board LED to the new one that fits on the Front Panel we need to change the deafult GPIO connector. For that purpose, just edit the file /boot/config.txt and set the following value to the respective new GPIO (in the schematics above it’s the GPIO 16):

dtparam=act_led_gpio=16

Configuring the I2C LCD

[1] Configure the I2C Interface

[2] Install Dependencies

 
$ sudo apt-get install i2c-tools 
$ sudo apt-get install python-smbus
$ sudo modprobe i2c-dev

$ i2cdetect -y 1 # get I2C address param 0 if rp1

$ wget https://raw.githubusercontent.com/emcniece/rpi-lcd/master/RPi_I2C_driver.py #change I2C address

[3] Sample Scripts

Hello World on LCD:

 
import I2C_LCD_driver
from time import *

mylcd = I2C_LCD_driver.lcd()

mylcd.lcd_display_string("Hello World!", 1)

Showing Local IP Address:

 
import I2C_LCD_driver
import socket
import fcntl
import struct

mylcd = I2C_LCD_driver.lcd()

def get_ip_address(ifname):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    return socket.inet_ntoa(fcntl.ioctl(
        s.fileno(),
        0x8915, 
        struct.pack('256s', ifname[:15])
    )[20:24])

mylcd.lcd_display_string("IP Address:", 1) 

mylcd.lcd_display_string(get_ip_address('eth0'), 2)

[4] Troubleshooting

It’s possible that the 16x2 LCD will be misconfigured at the contrast level. To adjust it, just turn the potentiometer screw of the I2C conversor (on both directions) until you get the right contrast (positioned in the back of the LCD).

Assembly & Final Result