At present, Timer can only reset by redstone signal, but can't stop it.

• Redstone Reset(keep running, get a redstone signal to reset, keep redstone signal will ignore)
• Redstone Start(not running, get a redstone signal to start, keep redstone signal to keep running, not redstone will stop and reset)
• Redstone Continue(keep redstone signal to start/continue, not redstone will pause, 1 tick redstone signal to reset)

Fixed by 59d51f5, which will be in the next release.