2 Peripheral Overview
The following table shows the peripheral overview of the entire AVR SD family.
| Feature | 
                                          
                                           AVR32SD20  | 
                                          
                                           AVR32SD28 AVR64SD28  | 
                                          
                                           AVR32SD32 AVR64SD32  | 
                                          
                                           AVR64SD48  | 
|---|---|---|---|---|
| Pins | 20 | 28 | 32 | 48 | 
| Max. frequency (MHz) | 20 | 20 | 20 | 20 | 
| Clock Controller (CLKCTRL) with Clock Failure Detection (CFD) and Clock Frequency Measurement (CFM) | 1 | 1 | 1 | 1 | 
| Clock Failure Detection (CFD) | 2 | 2 | 2 | 2 | 
| Clock Frequency Measurement (CFM) | 2 | 2 | 2 | 2 | 
| 16-bit Timer/Counter type A (TCA) | 1 | 1 | 1 | 1 | 
| 16-bit Timer/Counter type B (TCB) | 4 | 4 | 4 | 4 | 
| 12-bit Timer/Counter type D (TCD) | 1 | 1 | 1 | 1 | 
| Real-Time Counter (RTC) | 1 | 1 | 1 | 1 | 
| USART | 2 | 3 | 3 | 3 | 
| SPI | 2 | 2 | 2 | 2 | 
| TWI/I2C(1) | 1(1) | 1(1) | 2(1) | 2(1) | 
| 10-bit ADC (channels) | 2 (13) | 2 (19) | 2 (19) | 2 (24) | 
| Analog Comparator (AC) | 3 | 3 | 3 | 3 | 
| Digital-to-Analog Converter (DAC) | 1 | 1 | 1 | 1 | 
| Zero Cross Detector (ZCD) | 2 | 2 | 2 | 2 | 
| Configurable Custom Logic Look-up Table (CCL LUT) | 6 | 6 | 6 | 6 | 
| Error Controller (ERRCTRL) | 1 | 1 | 1 | 1 | 
| Synchronous Watchdog Timer (SWDT) | 1 | 1 | 1 | 1 | 
| Watchdog Timer (WDT) | 1 | 1 | 1 | 1 | 
| Event System (EVSYS) channels | 6 | 6 | 6 | 6 | 
| General Purpose I/O | 15 | 21 | 25 | 40 | 
| PORT | PA[7:0], PC[3:1], PD[7:4] | PA[7:0], PC[3:0], PD[7:1], PF[1:0] | PA[7:0], PC[3:0], PD[7:1], PF[5:0] | PA[7:0], PB[5:0], PC[7:0], PD[7:0], PE[3:0], PF[5:0] | 
| PORT pins with MVIO capability | PC[3:1] | PC[3:0] | PC[3:0] | PC[7:0] | 
| External interrupts | 15 | 21 | 25 | 40 | 
| CRCSCAN | 1 | 1 | 1 | 1 | 
| Unified Program and Debug Interface (UPDI) | 1 | 1 | 1 | 1 | 
Note: 
            
- The TWI/I2C can operate simultaneously as host and client on different pins.
 
