RadI2Cino - I2C replacement for the uBITX Raduino #ubitx

Jim Sheldon
 

Announding the RadI2Cino (prounounced "Rad ee too CEE no", an almost "Drop In" replacement for the original uBITX Raduino card.
The attached PDF file contains the complete information on it but here is a summary of the changes/enhancements incorporated in the
RadI2Cino from the original Raduino.

I2C is used so the 16 pin LCD display header has been eliminated.
The LCD display contrast pot has been eliminated.
The 16 pin and 8 pin uBITX headers are retained and connect in the original fashion.
Arduino NANO I/O pin assignments have been rearranged to free up digital and analog I/O pins.
     a) D8, D11, D12 now used for key, paddles, and PTT.
     b) D10 used for an A/B split selection button.
     c) D9, D13, A3, A6, A7 now available for other needs.
The LCD display is operated via an I2C bus connection.|
     a) Contrast control is now part of I2C interface "backpack".
     b) Larger, 4-line displays are supported.
The TO-220 5 volt regulator has been replaced by a surface mount 7805 1 amp regulator.
A surface mount 3.3 volt regulator has been added.
A 4-pin header has been added to give access to the I2C bus.
A logic level translator has been added to the I2C bus to protect the Si5351 clock chip.
Manufacturer-recommended RC de-bouncing for the rotary encoder phases has been added.
Provision is made for an optional dropping resistor to reduce regulator dissipation.
Several powering options are provided, selected by shorting jumpers.
     a) power everything through the NANO via the uBITX +12V rail**
     b) power the NANO from the uBITX +12V rail, and the rest via the 5V regulator**
     c) power everything from the board mounted 5 volt regulator.
     d) power the Si5351a from the NANO's 3.3 V output.
     e) power the Si5351a from the on-board 3.3 V regulator.
Though the PC board is slightly longer, mounting holes compatible with the LCD display are retained.
An additional 8 pin header is added for access to the newly free I/O pins.
Uncommitted PCB pads are provided to connect serial I/O and NANO Reset.
NANO mounting pads are intentionally oversized to allow for a low profile, machined pin, socket for the Nano.
Heavy use is made of silk-screened labels to identify signals and functions.

 ** If the optional dropping resistor is not used DO NOT EXCEED 12V when using these power options.

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