import hid import enum BIGSCREEN_VID = 0x35BD BEYOND_PID = 0x0101 USER_SIG_LENGTH = 512 CRC_INIT_VAL = 0xFF CRC_POLY = 0x07 class SigTag(enum.IntEnum): Invalid = 0xFF Serial = 0x01 RGB_Color = 0x02 Fan_Speed = 0x03 Prox_Disable = 0x04 Linkbox_v1 = 0x05 Prox_Cal = 0x06 FATP_Mode = 0x07 HMD_Serial = 0x08 Tracking_Serial = 0x09 def crc8(input_data: bytes) -> int: initval = CRC_INIT_VAL for bb in input_data: # for each byte, xor with the current value of CRC # then iterate over all 8 bits using the polynomial # to generate crc bits initval = initval ^ bb for _ in range(8): if(initval & 0x80): initval = ((initval << 1) & 0xFF) ^ CRC_POLY else: initval = (initval << 1) & 0xFF return initval def create_field(tag: SigTag, data: bytes) -> bytes: retbytes = bytes([tag, len(data)]) + data crc = crc8(retbytes) return retbytes + bytes([crc]) def create_signature(sig_fields: dict) -> bytes: sig_ptr = 0 sig_bytes = bytearray([0xFF]*USER_SIG_LENGTH) if(SigTag.Serial in sig_fields): # serial number newsig = sig_fields[SigTag.Serial] if(len(newsig) > 0): newblock = create_field(SigTag.Serial, newsig) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.HMD_Serial in sig_fields): newsig = sig_fields[SigTag.HMD_Serial] if(len(newsig) > 0): newblock = create_field(SigTag.HMD_Serial, newsig) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.Tracking_Serial in sig_fields): newsig = sig_fields[SigTag.Tracking_Serial] if(len(newsig) > 0): newblock = create_field(SigTag.Tracking_Serial, newsig) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.Fan_Speed in sig_fields): if(type(sig_fields[SigTag.Fan_Speed]) == int): newval = bytes([sig_fields[SigTag.Fan_Speed]]) else: newval = bytes(sig_fields[SigTag.Fan_Speed]) newblock = create_field(SigTag.Fan_Speed, newval) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.Prox_Cal in sig_fields): newblock = create_field(SigTag.Prox_Cal, sig_fields[SigTag.Prox_Cal]) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.RGB_Color in sig_fields): newblock = create_field(SigTag.RGB_Color, sig_fields[SigTag.RGB_Color]) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.Prox_Disable in sig_fields): if(type(sig_fields[SigTag.Prox_Disable]) == int): newval = bytes([sig_fields[SigTag.Prox_Disable]]) else: newval = bytes(sig_fields[SigTag.Prox_Disable]) newblock = create_field(SigTag.Prox_Disable, newval) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.Linkbox_v1 in sig_fields): if(type(sig_fields[SigTag.Linkbox_v1]) == int): newval = bytes([sig_fields[SigTag.Linkbox_v1]]) else: newval = bytes(sig_fields[SigTag.Linkbox_v1]) newblock = create_field(SigTag.Linkbox_v1, newval) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) if(SigTag.FATP_Mode in sig_fields): if(type(sig_fields[SigTag.Linkbox_v1]) == int): newval = bytes([sig_fields[SigTag.FATP_Mode]]) else: newval = bytes(sig_fields[SigTag.FATP_Mode]) newblock = create_field(SigTag.FATP_Mode, newval) sig_bytes[sig_ptr:sig_ptr + len(newblock)] = newblock sig_ptr = sig_ptr + len(newblock) return bytes(sig_bytes) def parse_sig(sig_bytes: bytes) -> dict: # reads the signature block and extracts the config data # data is in TLVC (Tag, Length, Value, CRC) format # Byte0: Tag, tells you what data field is saved # Byte1: Length, number of bytes in the Value # Byte2 to Byte 2+Length-1: Value, arbitrary data saved for this field # Byte 2+Length: CRC, 8-bit CRC code generated with polynomial 0x07 over all bytes (including tag) # with an initial value of 0xFF sig_ptr = 0 sig_fields = {} while(sig_ptr < USER_SIG_LENGTH): if(sig_bytes[sig_ptr] == SigTag.Invalid): # we reached the end of saved data, so this was valid # even if there's no data saved this can be a valid signature (all 0xFF) return sig_fields # Ensure there's enough room for a 1-byte field if(sig_ptr > (USER_SIG_LENGTH - 4)): # Tag will overrun end of signature region sig_fields['error'] = 'overrun' return sig_fields tag = sig_bytes[sig_ptr] taglen = sig_bytes[sig_ptr+1] # now ensure there's enough room for THIS field. Use the length data. if(sig_ptr > (USER_SIG_LENGTH - (3 + taglen))): sig_fields['error'] = 'overrun' return sig_fields tagval = sig_bytes[sig_ptr+2:(sig_ptr+2+taglen)] tagcrc = sig_bytes[sig_ptr+2+taglen] # check the CRC computecrc = crc8(bytes([tag, taglen])+bytes(tagval)) if(tagcrc != computecrc): sig_fields['error'] = 'crc mismatch' return sig_fields # Check if the tag is in our database if(tag == SigTag.Serial): sig_fields[SigTag.Serial] = tagval if(tag == SigTag.HMD_Serial): sig_fields[SigTag.HMD_Serial] = tagval if(tag == SigTag.Tracking_Serial): sig_fields[SigTag.Tracking_Serial] = tagval if(tag == SigTag.Fan_Speed): if(taglen != 1): sig_fields['error'] = 'tag length mismatch (Fan speed)' return sig_fields else: sig_fields[SigTag.Fan_Speed] = tagval if(tag == SigTag.Prox_Cal): if(taglen != 2): sig_fields['error'] = 'tag length mismatch (prox cal)' return sig_fields else: sig_fields[SigTag.Prox_Cal] = tagval if(tag == SigTag.RGB_Color): if(taglen != 3): sig_fields['error'] = 'tag length mismatch (rgb color)' return sig_fields else: sig_fields[SigTag.RGB_Color] = tagval if(tag == SigTag.Prox_Disable): if(taglen != 1): sig_fields['error'] = 'tag length mismatch (prox disable)' return sig_fields else: sig_fields[SigTag.Prox_Disable] = tagval if(tag == SigTag.Linkbox_v1): if(taglen != 1): sig_fields['error'] = 'tag length mismatch (linkbox v1)' return sig_fields else: sig_fields[SigTag.Linkbox_v1] = tagval if(tag == SigTag.FATP_Mode): if(taglen != 1): sig_fields['error'] = 'tag length mismatch (FATP mode)' return sig_fields else: sig_fields[SigTag.FATP_Mode] = tagval # any other tag should be ignored. can still be a valid config region, just means # there's a new field type that we don't know about yet sig_ptr = sig_ptr + 3 + taglen # length of data, plus the 3 fixed bytes (tag, length, crc) return sig_fields if __name__ == '__main__': bigs = hid.Device(vid = BIGSCREEN_VID, pid = BEYOND_PID) # load config region config_bytes = bytearray([0xFF] * USER_SIG_LENGTH) for i in range(16): bigs.send_feature_report(bytes([0, ord('U'), i])) newbytes = bigs.read(65, timeout=100) while(len(newbytes) == 0 or newbytes[0] != ord('U')): newbytes = bigs.read(65, timeout=100) newlen = newbytes[1] newsig = newbytes[2:(2+newlen)] config_bytes[(32*i):(32*i + newlen)] = newsig # print(config_bytes) config_fields = parse_sig(config_bytes) print('Found config data: ') print(config_fields) if(SigTag.Prox_Cal in config_fields): config_fields.pop(SigTag.Prox_Cal) print('Removing proximity calibration and saving new config:') print(config_fields) new_config_bytes = create_signature(config_fields) for i in range(16): bigs.send_feature_report(bytes([0, ord('W'), i]) + new_config_bytes[(32*i):(32*(i+1))]) newbytes = bigs.read(65, timeout=100) while(len(newbytes) == 0 or newbytes[0] != ord('$')): newbytes = bigs.read(65, timeout=100) bigs.send_feature_report(bytes([0, ord('V')])) newbytes = bigs.read(65, timeout=100) while(len(newbytes) == 0 or newbytes[0] != ord('$')): newbytes = bigs.read(65, timeout=100) print('Saved new config. Power cycle HMD.') else: print('Prox calibration not found. No changes were made.')