VMAC PiHat v2 Changes from v1


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
  • EEPROM Solder pads
  • 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)


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