alienFontDisplay

Display made of six eight-segment EL display units with per-display custom driver board and controller.

Scrolling display board that displays whatever string is published on a given MQTT channel over WiFi.

These displays were used in Russian tanks and missile launch consoles.

TBD

Design 225VAC 400Hz inverter that can supply ?mA (?W)
BOM
WiFi interface board
Firmware
Tests
Example code
Documentation

Display Pinout

Alphanumeric Font

Single Display and Driver Board

Driver PCB

Schematic

EL Displays

IEL-O-VI C63.396.208-02

Blue, Alien Font, Russian/Soviet Electroluminescent Display
[0-9] and [A-Z] (after a fashion)
- some characters are lower case and some are missing strokes
  - in particular, there isn't a center vertical stroke, so "T" and "I" are not so great
- seems to have been designed for Cyrillic characters
pinout
- 1: common
- 2: bottom horizontal (S)
- 3: bottom right angled (M)
- 5: n/c?
- 7: left vertical (L)
- 8: bottom left angled (M)
- 11: top right angled (M)
- 14: left vertical (L)
- 17: top horizontal (S)
- 20: top left angled (M)
per-segment capacitance (estimates)
- S (2x): 55 pFd
- M (4x): 90 pFd
- L (2x): 170 pFd

Power Supply Design

Specs
- 220VAC @ 400Hz
- 0.5-3mA per display
  - four displays: 12mA (max)
  - six displays: 18mA (max)
Design alternatives
- drive audio amp into (CT?) step-up transformer
- DC boost converter into H-Bridge

=========================

notes
- ~200V @ 400Hz
- not squarewave -- filter or triangle wave for constant dv/dt
- less bright at 50Hz, but last longer
- need current limiting resistor if power source has low internal resistance
  - e.g., 330K ohm @ 220V @ 50Hz
- 500 Hrs lifespan
- sine/square voltage up to 250V and 400Hz-5KHz
- decay time fractions of msec
- at least 6usec pulse
- no loss of brightness in pulses of 100usec at constant duty cycle
- most of drop in brightness occurs in first 200 hours of operation
  - relatively flat after that
- for best lifetime, maintain constant frequency and reduce voltage
- use current limiting resistor for supplies with internal resistance less than 1Kohm
- add 0.03-0.05ufd caps in parallel with electrodes to improve reliability
- nomenclature
  - I: indicator
  - EL: electroluminescent
  - color
    - O: one color
    - M: multicolor
    - P: raster
  - size (13x sizes)
    - VI: 34x40mm
    - II: 13x35mm
    - IV: 18x26mm
  - number of dots indicate brightness
- IEL-0-VI-101-246: 19x segment starburst with bar above and left and right commas
- constant power mode
  - 220V @ 400Hz
- constant brightness mode
  - 175-250V @ 1200Hz -- increases with service life
- 0.5-3 mA current
- DC will destroy the display
- can't multiplex displays -- need driver for each segment
- lifetime drops rapidly with supply frequency >400Hz
Links
Sparkfun EL Inverter (COM-10469 retired)
- input: 12VDC
- output: 70-110V (90V typ)
- frequency: 800-3500Hz (2000Hz typ)
Sparkfun EL Inverter (sourced from Amazon)
- input: 5VDC
- output: 225VAC (in afd circuit)
- frequency: 5-7KHz (in afd circuit)

=======================================================================================

SmartSocket for Alien Font displays
- use same protocol on daisy-chained 9600 baud RS232 (3v3?)
  - http://tayloredge.com/reference/Circuits/1386SmartSocket/SmartSockets.pdf
- build single-sided PCB that fits on back of display units
  - drive each segment individually
  - use common HV PSU
  - use circuits from SparkFun boards as they have been tested and shown to work
- need to select a PIC to use as the on-board controller
  - PIC18F16Q41: same as PIC18F16Q40 but has an opAmp
  - PIC18F16Q40:
    - 14pin device has six GPIOs on PortA and another six on PortC
    - has 1/2 UARTs
    - 64KB program FLASH, 4KB SRAM, 512B EEPROM
    - 18x GPIO, 2/3x 8b timers, 17x channels of 12b ADC, 2x 8b DACs, 4x DMA
    - 32b CRC with scanner, vectored interrupts, temperature indicator, NCO, PWM/CCP
    - C compiler
      - CCS: http://www.ccsinfo.com -- $200-$500
      - Hi-Tech: http://www.htsoft.com -- bought by Microchip
      - Microchip: http://www.microchip.com -- free student mode
      - MPLAB C18: microchip
      - MikroC: free student version with limits
      - https://www.microchip.com/en-us/development-tool/C18
    - $1.5 at Mouser (in stock)
      - PIC18F16Q40-E/SO
      - https://www.mouser.com/ProductDetail/Microchip/PIC18F16Q40-E-SO?qs=sGAEpiMZZMv0NwlthflBi%252BydFA3s6SRqoyEH6IOSDHM%3D
    - example: https://github.com/microchip-pic-avr-examples/pic18f16q40-quadrature-decoder
      - RA2: UART Tx programmer?
      - RB7: UART Tx
      - RB5: UART Rx
      - RB4, RB6, RA4, RA5, RC0-RC7: GPIO
    - PPS re-mappable input signals can be moved from default locations to other ports
      - UART outputs: DTR1, RTS1, TX1, DTR2, RTS2, TX2, DTR3, RTS3, TX3
      - UART inputs: RX1, CTS1, RX2, CTS2, RX3, CTS3
    - pin allocation table (default)
      - RB5: RX1
      - RB7: CTS1
      - RC1: RX2
      - RC2: CTS2
      - RC3: RX3
      - RC5: CTS3
- use shift registers?
- use I2C port expander?
display unit dimensions, pin and threaded spacer locations are not consistent across instances
Use SparkFun EL boards for proof of concept testing
EL Sequencer v23
- https://www.sparkfun.com/products/12781
- http://cdn.sparkfun.com/datasheets/Components/EL/SparkFun_EL_Sequencer_v23.pdf
- ATMega328P processor on-board
  - use "Arduino Duemilanove or Diecimila" board with FTDI USB dongle
- Gets HV from Sparkfun EL Inverter
  - not ideal -- need higher voltage and better frequency
- Drives HV to all segments of all displays
  - EL Escudo Dos pulls display commons to HV_GND
- D2-D9 used to drive EL_A-EL_H
  - EL_A: pin 2
  - EL_B: pin 3
  - EL_C: pin 7
  - EL_D: pin 8
  - EL_E: pin 11
  - EL_F: pin 14
  - EL_G: pin 17
  - EL_H: pin 20
- Sends six (active high) TTL signals to EL Escudo Dos to enable each display
  - ADC_0 (JP4:2): display #1
  - ADC_1 (JP4:7): display #2
  - ADC_2 (JP2:8): display #3
  - ADC_3 (JP2:7): display #4
  - ADC_4 (JP2:6): display #5
  - ADC_5 (JP2:5): display #6
EL Escudo Dos
- https://www.sparkfun.com/products/10878
- https://cdn.sparkfun.com/datasheets/Components/EL/EL_Escudo_Dos/EL%20Escudo%20Dos%20v21.pdf
- Pulls display common lines (pin 1) down to HV_GND
- EL_H: display #1 ... EL_C: display #6
- gets HV_GND and TTL display unit selector signals from EL Sequencer
- all SCRs have common HV connected to their tabs
  - and they have individual outputs to load and ground
- need to cut HV to tabs and connect them to the display common signals
  - and short all load outputs to HV_GND
misc
- mqtt listener
  - mosquitto_sub -t /displays/# -F "%I,%t,%p"
- commands
  - rssi
  - version
  - reset
  - rate[=]
  - scrollDelay[=]
  - pause[=]
  - display[=]
- e.g., mosquitto_pub -t "/displays/afd//cmd" -m "display=abcdefghijklmnopqrstuvwxyz0123456789"

jduanen/alienFontDisplay