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. 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. TC3 is paired with TC4, and TC5 is paired with TC6. TC7 does not support 32-bit resolution.

When paired, the TC peripherals are configured using the registers of the even-numbered TC (TC4 or TC6 respectively). The odd-numbered partner (TC3 or TC5 respectively) will act as slave, and the Slave bit in the Status register (STATUS.SLAVE) will be set. The register values of a slave will not reflect the registers of the 32-bit counter. Writing to any of the slave registers will not affect the 32-bit counter. Normal access to the slave COUNT and CCx registers is not allowed.