Single molecule mechanical experiments allow the controlled manipulation of proteins and the population of intermediate states within their high dimensional energy landscape. Here we report single molecule refolding measurements of domain 4 from the protein ddFilamin using a novel digital control scheme. First, the protein is unfolded mechanically to an intermediate state. An on-line detection scheme then detects population of the intermediate and rapidly switches to refolding conditions. This control scheme allows direct measurement of the refolding kinetics. A comparison to the results from conventional single molecule refolding schemes allows important conclusion on the structural relation between unfolding and refolding intermediates in this protein domain. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.