NCV7430
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18
Physical Address of the Circuit
The circuit must be provided with a node address in order
to discriminate this circuit from other ones on the LIN bus.
This address is coded on 6 bits, yielding the theoretical
possibility of 64 different devices on the same (logical) bus.
However the maximum number of nodes in a LIN network
is also limited by the physical properties of the bus line.
Beside the node address a 4 bit “GROUP_ID” identifier
is available. This “GROUP_ID” identifier is only evaluated
when the Broad bit is recognized as ‘0’. The “GROUP_ID”
identifier assigns the node to one of 16 groups. The node can
only be assigned to one group. The LIN message will use 16
bit locations for the Groups. When the Node “GROUP_ID”
identifier matches the bit in the message, the message will
be evaluated. Refer to Figure 8.
Group 15
Group ID 1111
Group ID
programmed
in NCV7430
Send by
The message can address one or more Nodes at the
same time by setting the appropriate Group bit(s).
Figure 11.
Group 14
Group 13
Master
Group 12
Group 11
Group 10
Group 9
Group 8
Group 7
Group 6
Group 5
Group 4
Group 3
Group 2
Group 1
Group 0
Group ID 1110
Group ID 1101
Group ID 1100
Group ID 1011
Group ID 1010
Group ID 1001
Group ID 1000
Group ID 0111
Group ID 0110
Group ID 0101
Group ID 0100
Group ID 0011
Group ID 0010
Group ID 0001
Group ID 0000
Resuming: The NCV7430 is individually addressable by
its LIN node address and cluster addressable via the “Group”
bits when ‘Broad’ is ‘0’.
NOTE: For the Set_Color_Short and Set_Intensity
commands the GROUP_ID bits are split. The
lower two bits are used to assign the NCV7430
to one of four groups for the color setting, while
the upper two bits are used to assign the device
to one of four groups for the intensity setting.
BAUD Rate
The NCV7430 device automatically distinguishes
between high and low baud rates.
A high baud rate of 19200 transmitted by the master will
be duplicated by the slave.
There are two low baud rates in use between the US and
Europe. They are 9600 and 10400. To eliminate possible
confusion between these two closely related frequencies, the
device is programmable via the OTP register to select
between the two frequencies (reference Table 8).
LIN Frames
The LIN frames can be divided in writing and reading
frames. A frame is composed of an 8−bit Identifier followed
by 2, 4 or 8 data−bytes and a checksum byte.
NOTE: The checksum conforms to LIN 1.3. This means
that all identifiers are validated with classic
checksum.
Writing frames will be used to:
• Program the OTP Memory;
• Configure the LED parameters (Modulation value etc);
• Control of the LED Outputs.
Whereas reading frames will be used to:
• Get status information such as error flags;
• Reading OTP for calibration by MCU;
• Verify the right programming and configuration of the
component.
Writing Frames
The LIN master sends commands and/or information to
the slave nodes by means of a writing frame. According to
the LIN specification, identifiers are to be used to determine
a specific action. If a physical addressing is needed, then
some bits of the data field can be dedicated to this, as
illustrated in the example below.
Identifier Byte Data Byte 1 Data Byte 2
ID
0
ID
1
ID
2
ID
3
ID
4
ID
5
ID
6
ID
7
phys. address command parameters (e.g. position)
<ID6> and <ID7> are used for parity check over <ID0> to <ID5>, conforming to LIN2.1 specification. <ID6> = <ID0> ⊕
<ID1> ⊕ <ID2> ⊕ <ID4> (even parity) and <ID7> = NOT(<ID1> ⊕ <ID3> ⊕ <ID4> ⊕ <ID5>) (odd parity).
