27.6.2.4 Counter Mode

The Counter mode is selected by the Mode bit group in the Control A register (CTRLA.MODE). By default, the counter is enabled in the 16-bit counter resolution. The following three counter resolutions are available:

• COUNT8: The 8-bit TC has its own Period register (PER). This register is used to store the period value that can be used as the top value for waveform generation.
• COUNT16: 16-bit is the default Counter mode. There is no dedicated Period register in this mode.
• COUNT32: This mode is achieved by pairing two 16-bit TC peripherals. In this mode, TC0 is paired with TC1, TC2 is paired with TC3, TC4 is paired with TC5, and TC6 is paired with TC7.

When paired, the TC peripherals are configured using the registers of the even-numbered TC . The odd-numbered partner will act as Client, and the Client bit in the Status register (STATUS.Client) will be set. The register values of a Client will not reflect the registers of the 32-bit counter. Writing to any of the Client registers will not affect the 32-bit counter. Normal access to the Client COUNT and CCx registers is not allowed.