$3\mathrm{.}2$ TheUpMode

In the up mode, the upperbound of TAR is set to any value that we choose. TAR counts from zero up

to the value of register TACCR$0.$ The timer has multiple channels and each channel has its own register

and comparator. The registers of Channels $0,1,2$ are TACCR$0,$ TACCR$1,$ TACCR$2,$ respectively. When

the timer runs in the up mode, the register of Channel $0,$ TACCR$0,$ becomes the upperbound of TAR.

Therefore, the up mode is inherently linked to Channel $0.$ The timeline below shows how TAR counts in

the up mode. When TAR reaches TACCR$0,$ it rolls back to zero and continues counting. Similar to the

continuous mode, when TAR rolls back to zero $($while counting$),$ the TAIFG flag is set by the hardware.