Elite-C

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Elite-C
Host port USB Type C
Microcontroller ATMega32U4
Voltage 5V
Clock speed 16 MHz
Digital I/O pins 24
I/O Voltage 5V
RAM 2.5 KB
Program memory 32 KB
EEPROM 1 KB
Boot loader DFU

The Elite-C is a microcontroller board made to be fully backwards-compatible with the Arduino Pro Micro. Its main features are a USB type C port and more IO pins.

Differences to the Pro Micro

Changes

  • The USB port is now USB type C mid-mount, which is both through-hole and SMD mounted. It should be tougher and not as easily torn off as the USB micro B port on the original Pro Micro.
  • The RAW pin on the Pro Micro has been replaced with PB0.
  • The bootloader is DFU.
  • The silk-screened print on the board lists the actual ATmega32U4 port and bit numbers, not Arduino numbering.

Additions

  • Five additional I/O pins are exposed on the short edge. (PBO replaces the old RAW pin, for a total of six new I/O pins, making the total 24 out of the ATmega32U4's 26)
  • There are also holes for the USB port, for an external USB breakout board.
  • There is now an additional VBUS pin above pin B0, allowing for easier connection of external USB ports.
  • A physical reset button.

Omissions

  • No indicator LEDs. The pins are instead available.
  • It has no voltage regulator and runs only on +5V.

Version history

Version 1

  • There is no on-board LED.

Version 2

  • A power LED was added, in the same position as on the Pro Micro.
  • A 500mA fuse was added for overcurrent protection.

Version 3.0

  • Castellated holes for flush mounting (where supported by a PCB).
  • A bad choice of the VBUS diode makes Master/Slave detection in split keyboards by checking VBUS not possible. (See below)

Version 3.1

  • The VBUS bug of version 3.0 is fixed.
  • The power LED was changed to blue and given a resistor so as to be less bright.
  • The reset button was exchanged for one with lower profile.

Version 4.0

  • VBUS pin added above pin B0, to allow proper use of external USB ports
  • The reset button was exchanged for one with even lower profile.
  • USB-C port changed to mid-mount type, board thickness changed to 1.6mm to accommodate
  • USB-C port is now the limiting factor to thinness of the board.

Compatibility

  • It is pinout-compatible with the Pro Micro, except that the RAW pin has been replaced with PB0. This poses a problem for a few keyboard PCBs that use VBUS to power other components (such as through a separate voltage regulator).
  • The USB port is slightly larger than the Micro-B port on the Pro Micro. This has caused problems with a few keyboard cases. (The board thickness has been reduced to alleviate this)
  • The reset button also adds thickness compared to the Pro Micro. It was was replaced with a lower-profile button in version 3.1.

Bugs

  • On some V1.0 boards, the Shottky diode is not soldered on properly.
  • Version 3.0 uses a Schottky diode between VBUS and Vcc which has noticeable reverse leakage current. This makes automatic Master/Slave detection on split keyboard not work.[1] This was fixed in version 3.1. A workaround for QMK involves adding #define SPLIT_USB_DETECT in config.h. This enables another detection method that instead waits after startup to check if a USB connection with a host exists.
  • Versions older than v4.0 don't have VBUS broken out, causing possible difficulty using external USB ports properly.

Pinout

Arduino AVR AVR Arduino
USB port
 
Elite-C v4 Pinout Diagram
Elite-C V4 Pinout Diagram
 
   
TX D1 PD3 PB0 (was RAW on Pro Micro)
RX D0 PD2 GND
GND Reset
GND Vcc (+5V)
SDA D2 PD1 PF4 D21 A3
SCL D3 PD0 PF5 D20 A2
A6 D4 PD4 PF6 D19 A1
D5 PC6 PF7 D18 A0
A7 D6 PD7 PB1 D5 SCLK
D7 PE6 PB3 D14 MISO
A8 D8 PB4 PB2 D16 MOSI
A9 D9 PB5 PB6 D10 A10
PB7 PD5 PC7 PF1 PF0
  • Internal pins: D+, D-

References

  1. Keebio blog—The Case of the Wayward Elite-C. Dated 2019-11-05. Retrieved 2019-12-08