External display with rotary encoder, back and home button and LEDs

thingiverse

#External LCD2004 display with rotary encoder, back and home button and LEDs Made for Anet A8 and marlin firmware. ###Display By using an I²C display, the number of required pins could be reduced to 2 pins. It's a default LCD2004 with a PCF8575 port expander as sold for Arduino. ###Keys The Anet LCD2004 uses a resistor network to encode the buttons to one pn. I'm emulating that. The rotary emulates the center button. Up and down are omitted on this pin, since the encoder replaces their function. Left and right are emulated mapped to back and home by the marlin firmware, which is a nice feature. I'm using (cheap) TTP223 buttons, so I need a transistor to map the +5V signal to 0V and GND to N/C. If you'd use switches, you'd omit the resistors (470 Ohm) at J_HOME and J_BACK as well as the transistors and connect the switch to collector and emitter (outer pins). ###Encoder On the encoder, make sure to remove the switch's pullup resistor if there is one. The pullup on the CLK, DT pins may and probably should remain. ###LED I'm using common anode RGB led. Since one pin can drive one LED, I included a LED driver on the PCB: the lower three transistors and their resistors. I had no space to place the resistor for green at the bottom, so I put it next to the 10-pin connector. The LED driver is connected by three jumper wires which I could not place in Fritzing without hiding the PCB, so I marked the connection points in red, green and blue. ###PCB The yellow lines are wires on the underside, the orange lines on the top side. Gren circles connect both sides. The orange wires are insulated and connect only at the ends (I ommitted changing the side in Fritzing right next to the connectors). Most resistors are standing upright (circles), the black line is the location of the other leg. At the right hand side, you see a yellow line hiding an orange line. ###Connectors On **J_HOME** and **J_BACK**, the TTP223 sensors should be soldered to the **underside** of the PCB. Top is VCC, middle is sensor and bottom is GND. I put in some wire to connect the TTP to the PCB. **J_LCD** is GND, VCC, I²C SDA, I²C SCL, from top to bottom. **J_ENCODER** is CLK, DT, SW, VCC, GND. **J_RGB_LED** is Blue, Green, VCC, Red from left to right **J_IN** is to be connected to the LCD connector on the Anet A8. The pins are: |Left|Right| |-|-| |GND|+5V| |Blue_LED (A4)|ENC_CLK (RX1)| |Green_LED (A3)|ENC_DT (TX1)| |Red_LED (A2)|I²C_SCL| |ADC_KEYPAD (A1)|I²C_SDA| ### Configuration You'll need Marlin bugfix-1.1.x since I needed to fix some bugs in order to configure this LCD. I will update to 2.0.x soon. You could just apply my patches, too (ask for them), but then you'd not get the other bugfixes. Look at the sample Configuration.h.txt: It tells you to comment out the ZONESTAR_LCD which is used by the A8. Then search for the #define RGB_LED and edit the settings in your configuration accordingly. The section below "I²C-2004-Display and ADC key" goes to the end of your Configuration.h ### Encoder button I recommend https://www.thingiverse.com/thing:2549137 It was a little bit too deep for my encoder; I dropped piece of junk into the opening and it works well now. ###Version 1 The LCD screwholes in the cover are slightly off to the right hand side. Back button too thin to be visible Backside was work in progress ###Version 2 I moved the screw holes to the left and made them be longer and enlarged the line of the back button. I did not re-print the front cover, though; if you do and if it fits (or doesn't), please comment. Back side and cable cover printed well. ###Credits The LCD dummy I used is https://www.thingiverse.com/thing:2849816 (I don't think using it as a dummy qualifies as a remix, please correct me if I'm wrong)