Wiki VMAC PiHat v1 to v2 Changes

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VMAC PiHat v1
VMAC PiHat v2

    VMAC PiHat V2 is a compliment to the original V1 board.   v2.4 is the current version.

    At a glance changes:

    • On Screen Display Graphics With Matrix Switching
    • Video Signal Detectors on Three Video Inputs
    • Separate Pi Audio Matrix Inputs
    • Dedicated 3V3 Regulator
    • Removed 5V DC Input Regulator
    • Improved Matrix/OSD matching
    • Remove Input Diodes
    • Increased Test Points
    • EEPROM Addressable from User Programs and Scripts
    • Additional User LED

    PCB v2.4 Full details here

    The principle changes between V1.1 to V2.0 and V2.4 are listed below:

    • Increased RCA dedicated inputs to 6 x Audio or Video
    • Separated Pi Audio L/R Loopback from Input 5/6. They now go to separate Matrix Inputs for increased flexibility
    • Included new OSD Graphics with fully selectable Matrix switch control to allow OSD only or OSD with Video (any input)
    • Included new on-board automatic video detectors (for receivers with no squelch or CCTV / FPV camera use)
    • Removed 5v regulator due to heat dissipation from LDO and importantly gives back room on board for OSD as did not want to populate two sides
    • Changed PiHat 3v3. No longer taken from Pi 3v3 on header. Now uses new dedicated 3v3 regulator. This reduces current and increases flexibility for other CPU boards/types.
    • LEDs now in a row, just to make it clearer
    • Input diodes pad size increased slightly to make user hand soldering easier
    • DTMF input solder pad jumper to easily select preference from Matrix Out 8, static Input 6 or JST Header
    • Remove Input Diodes (v2.4)
    • Added rear solder jumper to enable EEPROM to be used on the PI, or on the I2C bus for general use. (v2.4)

    v2.0 to v2.4

    • OSD CS
    • OSD RST
    • EEPROM Solder pads
    • TP OSD LOS
    • OSD to Matrix matching – add R/C
    • Move solder pads to underside
    • Add Input 2 and Input 4 PCB pads for test and development use
    • OSD input and output matching and level updates
    • Video Detect LOS Level shifter on each output
    • Add additional test points
    • Remove input protection diodes
    • Add additional User LED on RTS GPIO 17

    PCB v2.0 Developer Edition 

    PCB v2.3 Internal Testing

    GPIO Changes (Existing software will work apart from tweaking DTMF D1 – new test code will be provided)

    • Moved DTMF D1 from GPIO 10 to GPIO 19 (To clear SPI bus for MAX7456)
    • GPIO SPI now goes to the OSD MAX7456
    • The unused GPIO 18, 23 and 24 are now used for the Video Detector Auto Signal Sensing VD_1, VD_2 and VD_3
    • OSD RST Enable/Disable on GPIO25


    • Add 1 x 3v3 Regulator (MCP1703 Low Quiescent Current LDO Regulator)
    • Add 3 x Auto Video Input Detectors (MAX7461)
    • Add 1 x OSD (MAX7456)
    • Add 1 x 3v3 Power LED
    • Add 1 x SPI level shifter for MAX7456
    • Remove 5v Regulator and DC Input Jack
    • Remove Set of Input Diodes (v2.4)
    • Update Passive Matching Components between Matrix and OSD (v2.4)

    Updated PiHat V2.0 and v2.4 schematics can be found here

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