In order to reduce the cost of Manchester decoding scheme in the traditional optical module industry and improve itscompatibility and reliability, a low-cost Manchester decoding scheme for optical modules is proposed. Firstly, the combined circuit of sampling resistor and opamp is used to preprocess the signal to solve the problem that the sampled signal amplitude is toosmall or saturated under different light intensity conditions and cannot be decoded. Secondly, the programmable counting array（PCA） inside the controller is used to capture the edge and calculate the duration of the signal to solve the problem of signal synchronization. In the process of synchronization judgment, the duration tolerance design is introduced, and the loss of data frameheader is optimized, which significantly improves the anti-interference ability of the decoding scheme. Finally, the programmablelogic unit（CLU） and timer inside the controller are used to extract the signal clock, and the signal is sent to the internal serial peripheral interface （SPI） module to complete the decoding, so as to improve the decoding efficiency and solve the problem of resource consumption and decoding compatibility of the controller. The test results show that the scheme can decode data accurately and stably, and meet the practical application requirements.