27.4.4.2.2 CCPxRB = CCPxRA + 1
When the value of CCPxRB is one greater than the value of CCPxRA and both registers are less than the period register, an output pulse that is one CCP clock cycle wide is generated.
When the value of CCPxRB is one greater than the value of CCPxRA and both registers are less than the period register, an output pulse that is one CCP clock cycle wide is generated.