DekTec DTM-3237 DVB-S2 Receiver - Manual (Page 36)

DTM-3237 – OEM DVB-S2 Receiver with DVB-ASI Output
User Manual
36
Figure 6: Read-command for the device type setting
The command consists of the following parts:
 Start character ‘STX’
 Two hexadecimal address characters (“60”)
 Two hexadecimal category characters (“01”)
 Two hexadecimal setting characters (“05”)
 A read character ‘R’
 Two hexadecimal checksum characters (“82”)
 End character ‘ETX’
Figure 7 shows the two possible replies from the command in Figure 6. The replies are similar to the
commands with the exception of the data-characters or the read character. On a successful command,
the reply-data is set to the corresponding data 3237 (0x00000CA5). When the received command
cannot be executed, the read character is set to the ASCII character ‘E’ and the data is removed. In
both cases the checksum is updated.
Figure 7: Reply after a device type read-command (successful and error)
I 2 C read command
Figure 8 shows the communication sequence used to issue a read frequency command (category
0x90, setting 3). The returned data consists of the frequency.
Figure 8: Send frequency read-command
The command consists of the following bytes:
 Address and I 2 C write-bit (0x60 and ‘0’)
 Category byte (0x90)
 Setting byte (0x03)
 Read byte (0x01)
 Index bytes (0x00 and 0x00)
 Checksum (0x0C, see Table 2). The checksum is computed with the address and without the I 2 C
write-bit.
Figure 9 is the reply-sequence that may be executed after the read-command of Figure 8. After
addressing this device, the bytes from the command are repeated followed with the 4-byte frequency.