'HUB75 test 6bit color 2bit per component(RGB)and some fill bits = 1byte      |
' tested with "ES-P2.5-I Pin2dmd led panel" 1/16 scan from Ali-Express
' gp0  RED0              Connection HUB75
' gp1  RED1
' gp2  GREEN0                 +----+
' gp3  GREEN1            RED0 |1 16| GREEN0
' gp4  BLUE0            BLUE0 |2 15| GND
' gp5  BLUE1             RED1 |3 14| GREEN1
' gp6  A                BLUE1  4 13| NC
' gp7  B                    A  5 12| B
' gp8  C                    C |6 11| D
' gp9  D                  CLK |7 10| LATCH
' gp10 CLK                /OE |8  9| GND
' gp11 LATCH                  +----+
' gp12 /OE
' The reduction to only 6bit was usefull to minimize the time for preparing
' display-data (pack and mix now~1ms), The PIO would be quick enough for more!
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