Example – Read physical address 0x4000C000 :

| Type (1 byte) | Length (2 bytes) | Value (variable) | |---------------|------------------|-------------------|

AT+DIAG=1 If blocked, TXD falls back to sending raw USB_DEVICE_REQ_SET_FEATURE to enable test mode. Each TXD command is a TLV (Type-Length-Value):

55 53 42 43 01 00 00 00 00 00 00 00 00 00 00 00 The device responds with a configuration descriptor containing max packet size (e.g., 0x200). TXD then requests switch to diag mode via: