System Clock Enable Register
| USBCLK | Enable USB FS Clock |
| PCK0 | Programmable Clock 0 Output Enable |
| PCK1 | Programmable Clock 1 Output Enable |
| PCK2 | Programmable Clock 2 Output Enable |
| PCK3 | Programmable Clock 3 Output Enable |
| PCK4 | Programmable Clock 4 Output Enable |
| PCK5 | Programmable Clock 5 Output Enable |
| PCK6 | Programmable Clock 6 Output Enable |
| PCK7 | Programmable Clock 7 Output Enable |