ESP32-TERM

Features

• ESP32 Module
  • UART interface
  • Keyboard/Mouse interface
  • Drives VGA video
  • Runs FabGL ANSI/VT Terminal firmware
• "Typical" Serial Terminal Connectors
  • Connectors down long side of the card
  • VGA
  • PS-2 keyboard
  • PS-2 mouse
  • Audio jack
  • DE-9 Serial
  • 5V DC on USB-B
• "Special" connectors
  • Connectors down the short side
  • Use with cards like SIMPLE-68008 which have FTDI connections
  • FTDI connector - 6-pin
  • 5V connector
• Programmable LED on P14
• 145x95mm size
  • 135x85mm hole mounting spacing
  • Can mount between 150x100mm (4"x6") clear acrylic sheets
• (4) 4-40 mounting holes

ESP-32 Module

• Uses the ESP32 DevKit ESP32-WROOM GPIO Pinout
• On board Blue LED = Arduino Pin 2
• There are various modules out there with different pinouts, but this card uses this one

ESP-32 Module Pinout

"Chip" on the module

ESP32 Pin Usage

• GPIO Pin Assignment

Module Features

• Architecture: Xtensa Dual-Core 32-bit LX6
• CPU frequency: up to 240MHz
• Total RAM available: 528KB (part of it reserved for system)
• BootROM: 448KB
• Internal FlashROM: none
• External FlashROM: code and data, via SPI Flash; usual size 4MB
• GPIO: 34 (GPIOs are multiplexed with other functions, including external FlashROM, UART, etc.)
• UART: 3 RX/TX UART (no hardware handshaking), one TX-only UART
• SPI: 4 SPI interfaces (one used for FlashROM)
• I2C: 2 I2C (bitbang implementation available on any pins)
• I2S: 2
• ADC: 12-bit SAR ADC up to 18 channels
• DAC: 2 8-bit DACs
• RMT: 8 channels allowing accurate pulse transmit/receive
• Programming: using BootROM bootloader from UART - due to external FlashROM and always-available BootROM bootloader, the ESP32 is not brickable

Connectors

P1 - VGA

• DB-15HD connector
• 64-colors (2:2:2)
• ESP32 pins

  HSync => GPIO23
  VSync => GPIO15
  R0    => GPIO22
  R1    => GPIO21
  G0    => GPIO19
  G1    => GPIO18
  B0    => GPIO5
  B1    => GPIO4

VGA - Resistor Selection

• ESP32 has a 3.3V driver which can drive more than 10 mA
• Ideal case drive current
  • 0.7V (full scale VGA level) into 75 Ohms = 9.33 mA
  • 2/3 of the current or 6.16 mA comes from the lower value resistor (digital most significant bit)
  • 1/3 of the current or 3.08 mA comes from the higher value resistor (digital least significant bit)
• R-2R values
  • Ideal resistor values are 417.9 ohms and 835.7 ohms
  • Standard value 1% resistors
  • 1% standard values are 422 (Mouser), 845 (Mouser) Ohms
    • Get closest values
    • 0V, 0.228V, 0.460V, 0.693V
• Voltage steps are:

• Current steps are:

Video DAC LTSpice Simulation

• Video DAC Simulation files
• Video is 2:2:2 - R:G:B

Summing Video Resistor DAC

• Best values (1%)
  • 422, 845
  • 470, 820 are close/standard values
• 0.7V into 75 Ohm VGA load
• 3.3V drive
• ESP32 has 40 mA drive
  • Uses 8 mA (max)
• Output in 4 equal voltage steps

P2 - PS/2 Keyboard

• Purple DIN 6 connector
• 5V power to the keyboard
• Shift 3.3V levels of the ESP32 to 5V of the keyboard/mouse
• ESP32 pins

  KBDAT   => GPIO32
  KBCLK   => GPIO33

P3 - PS/2 Mouse

• Green DIN 6 connector
• 5V power to the keyboard
• ESP32 pins

  MSEDAT   => GPIO27
  MSECLK   => GPIO26

P4 - Audio Out

• Mono output wired on both pins (ring/tip) of stereo 3.5mm Jack
• Line level outputs
  • Requirs amplification
• ESP32 pins

  AUD   => GPIO25

P5 - RS-232

• On-board TTL to RS-232 converter
  • Swings +/- 10V
• DB-9 Female
• DCE wiring

DCE - RS-232 Connections

• This card has a DCE connector
  • The DCE (peripheral) has the female DB-9 connector
• The DTE (Host CPU) has the male DB-9 connector

• ESP-32 pins

  RX2    => GPIO34
  TX2    => GPIO2
  RTS    => GPIO13
  CTS    => GPIO35

P6 - 5V Power (USB)

• USB-B connector
• Power only (no data)
• Power can be sent out on J1 to external Processor card (like SIMPLE-68008 card)

J1 - 5V Power Header

• 2z3 right angle header
• Can be used for power in or out of the card
  • Only one power source can be used with the card

J2 - FTDI Power in/out Header

• 1x2 right angle header
• Don't install jumper if an external FTDI interface with 5V power out is used

J3 - FTDI Header

• 1x6 right angle header
• Most recent (2020-02) ANSI terminal uses pin 34 for Rx
• Pinout

1. GND
2. RTS (from ESP32)
3. 5V (Power in if J2 is installed)
4. RX (to ESP32)
5. TX (from ESP32)
6. CTS (to ESP32)

• ESP32 pins

  RX2    => GPIO34
  TX2    => GPIO2
  RTS    => GPIO13
  CTS    => I35

Connections to SIMPLE-68008 Card

• 1:1 connection to SIMPLE-68008 Card

ESP32-TERM			SIMPLE-68008
Pin	Signal		Pin	Signal
1	GND		1	GND
2	RTS (out)		2	CTS (in)
3	+5V		3	+5V
4	RX (in)		4	TX (out)
5	TX (out)		5	RX (in)
6	CTS (in)		6	RTS (out)

Connect to FTDI card

• Set FTDI jumper to 5V (image below shows jumper set to 5V)

J4 - Serial Source Selection Header

• 2x3 header
• Select either RS-232 connector or FTDI connector
• Silkscreen shows the appropriate side
  • Both left for TTL level signals (via FTDI connection)
  • Both right for RS-232 level signals

Software

• FabGL ANSI Terminal
  • Using ANSI/VT Terminal for the ESP32 application
• Programmed using Arduino IDE

FabGL Libraries

• FabGL - ESP32 Display Controller and Graphics Library
• FabGL Github repo

FabGL GPIOs assignment

• From here

  VGA
    HSync => IO23
    VSync => IO15
    R0    => IO21
    R1    => IO22
    G0    => IO18
    G1    => IO19
    B0    => IO4
    B1    => IO5

  Audio
    AUD   => IO25

  PS/2 - Keyboard
    DAT   => IO32
    CLK   => IO33

  PS/2 - Mouse (Not used)
    DAT   => IO27
    CLK   => IO26

  UART - UART2
    RX    => IO34
    TX    => IO2
    RTS   => IO13
    CTS   => I35

FabGL Arduino library

• Using FabGL library v1.0.9

Using Latest FabGL builds (not necessary to run the ANSITerminal)

• Fabrizio does a nice job of keeping his Arduino libraries up to date but if you want a bleeding edge experience, you can download his code from GitHub. Note, he's in active development so things often change.

Here's how I did it

• Install drivers via Arduino from the Library Manager
  • These are not necessarily the latest files
• Move the FabGL from the Arduino libraries file folder to the desktop
• Copy the FabGL from the GitHub download to the Arduino files folder (where you removed the other folder)
  • Examples will now be the latest.
• Compile/download/test the new files. You know it works if you now get sound from Space Invaders.
• Save as where you would normally save your Arduino sketches.

Arduino Programming

• Installing the ESP32 Board in Arduino IDE (Windows, Mac OS X, Linux)
• Select the board : DOIT ESP32 DEVKIT V1

• Select the application
  • File, examples, FabGL, examples, VGA, AnsiTerminal

• You may have to remove the module from the card to program it
  • Pins on the card collide with download
• If you try to upload a new sketch to your ESP32 and you get this error message “A fatal error occurred: Failed to connect to ESP32: Timed out… Connecting…“. It means that your ESP32 is not in flashing/uploading mode
  • You will need to press the boot button on the ESP32 module and release it after the Connecting message appears in the IDE

• Press the “Upload” button in the Arduino IDE to upload your sketch
• After you see the “Connecting….” message in your Arduino IDE, release the finger from the “BOOT” button:

Other Builds

• FabGL Serial Terminal - TTL and RS232
  • Designed and built by FabGL author
  • For sale on Tindie

• ESP32 ALTAIR EMULATOR GETS SPLIT PERSONALITY - Hackaday page
  • FabGL derived build

Checkout

Rev 1

• Check 5V power/ground short at J1
• Loopback Tx>Rx ant RTS > CTS
• Power up board via USB-B P6
• Lights will illuminate on ESP module
• Set baud rate (38,400)
• Enable RTS/CTS
• Type on keyboard, loops back
• Card works

Mechanicals

Assembly Sheet

• ESP32-VGA Interactive BOM