I am developing an MCU software code to control PN532 via I2C. The HREQ and IRQ are used in the communication. The communications with success replies from PN532 throughout SAMConfiguration, InListPassiveTarget and InDataExchange (Authentication). After the above, falling edge of HREQ leads to IRQ low and SCL is stuck low. This disables SLV,48 sending. Please advise why the symptom of SCL stuck low forever is. Thanks.