I understand that Federal bank/Goverment can manipulate the currency market and devalue its currency by printing more money or buying foreign currencies/assets (essentially increasing the supply of home country's currency). Devaluation eventually leads to cost-push/demand-pull inflation (not necessarily though, for eg: in times of recession, this might not happen). To combat inflation, interest rate would need to increase.
However, on the other hand, another theory states that - lower interest rates gives rise to inflation and eventually leads to currency devaluation.
What I cannot get my head around is what is the cause and what is its effect? Or do they function in sync and are basically two different tools of goverment to maintain the balance and control the economy?