I think you'll need hardware SPI for SDcard to be fast enough, which means not using pin 11 for PWM - you have pins 3 and 9 available which don't clash with the hardware SPI pins.
I think you'll need hardware SPI for SDcard to be fast enough, which means not using pin 11 for PWM - you have pins 3 and 9 available which don't clash with the hardware SPI pins.