OC3A is on pin D6~ for 32 pins mcus

[trimarco232]

says we want to use PD1 (pin n°31) as TXD of the USART : OC3A is no more available as PWM output for this pin
but we need 8 PWM outputs
the solution might be (I didn't test it yet) :

1. at pin D6~ , output OC3A :
   PMX1 Bit 2 C3AC = 1 = OC3A output to QFP48/AC0P
2. at pin A0 (PC0) , use OC0A* output :
   PMX0 Bit 3 C0AC0 : OC0A Auxiliary output control
   The 0C0A output is controlled by the C0AC0 bit in conjunction with the C0AS bit of the TCCR0B register:
   { C0AC0, C0AS } = 10 = 0C0A output to PC0
   in this case , one probably don't have to worry about the OC0AS Bit of TCCR0B ...