The DP83822 supports an IEEE 1588 indication pulse at the SFD (start frame delimiter) for receive and transmit paths. The pulse can be delivered to any of the following pins: LED_0, LED_1 (GPIO1), COL (GPIO2), RX_D3 (GPIO3), INT/PWDN_N and CRS. The 1588 Time Stamp pulse indicates the actual time the symbol is presented on the lines (for transmit), or the first symbol received (for receive). The exact timing of the pulse can be adjusted via the IEEE 1588 PTP Configuration Register (PTPCFG, address 0x003F). Each increment of phase value is an 8-ns step.
There are three registers that are able to control the routing of the IEEE 1588 transmit and receive indications. The IEEE 1588 PTP Pin Select Register (PTPPSEL, address 0x003E) is able to route both transmit and receive indications to LED_0 (GPIO1), COL (GPIO2), CRS and INT/PWDN_N, which is also found in the TLK105L and TLK106L PHYs. Two additional registers in the DP83822 allow for additional pin selections and a centralized location for GPIO controls through the use of the IO MUX GPIO Control Register #1 and #2 (IOCTRL1 and IOCTRL2, address 0x0462 and address 0x0463).