How to implemement a check sum

Hi , I’m trying to make a connection between my imp and arduino using RF modules, in arduino control the data by the UART , my imp must also receive the problem is that my data are not received quite right and say I make a checksum but I can not implement it in the imp… leave my 2 codes please help me…

The code functionality will more often than not depend on the make of RF module used and associated library. Which RF modules are you using.

For imp there is also the uart class event flags method which may help you.