What arduino board are you using? some use different pins? What pins are you using?
What is the I2C address of the slaves?
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What is the ADC resolution you are requiring?
I tried looking at for ADC resolution
PWMs (8 to 32 bit)
PWMs with Dead band (8 to 32 bit)
Counters (8 to 32 bit)
Timers (8 to 32 bit)
UART 8 bit with selectable parity (up to 4)
SPI master and slave (up to 4 each)
I2C slave and multi-master (1 available as a System Resource)
Cyclical Redundancy Checker/Generator (8 to 32 bit)
IrDA (up to 4)
Pseudo Random Sequence Generators (8 to 32 bit)
It was not in Features that I saw?