SIG40 Datasheet, PDF (7/12 Pages) Yamar Electronics Ltd. – for DC-LIN Asynchronous Communication Over Noisy Lines

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4 OPERATION
4.1 Message Construction
The host constructs a message from bytes of data sent to its UART. The device receives this data on
its HDI data-In line. The 1^st low input bit (start bit) starts the signaling transmission, and the 10^th high bit
(stop bit) stops the transmission. If all bits, including the 10^th bit, are low, the transmission continues
until a bit becomes high, but no more than 31-bit duration. It is considered as the Synch_Break Field of
the LIN protocol. The stop bit stops the transmission unless a new byte is received from host. The total
byte length does not change. The data latency between transmitter and receiver is about four bits.
4.1.1 LIN Protocol Messages
In order to comply with the LIN protocol, transmission of two kinds of bytes are allowed:
1. Bytes beginning with a start bit, followed by 8 bits and ending with a stop bit.
2. Bytes beginning with a start bit followed by a number of zeros ranging from 9 to 30 bits and
ending with a stop bit.
4.1.2 Commanding the SIG40
Writing and reading to/from the internal Control registers (See 4.2) using write and read commands set
the device behavior.
The registers are set by power-up Reset to operate at 19.2KBps, F0 = 5.5Mhz and F1 = 6.5Mhz.
Writing into the registers allows changing the selectable frequencies, the bit rate, and the operating
frequency. It also allows activating the automatic sleep feature and the automatic response to received
bytes feature.
4.1.3 Transmit
Upon detection of a start bit in HDI, the SIG40 starts to transmit modulated signal to the DC line
according to the set-up channel frequency and bit rate.
Note: After transmission, it takes duration of 2 bits before the device starts to listen to the DC-line.
4.1.4 Receive
When not transmitting, the SIG40 listens to the DC line in order to:
• Detect and decode a legal signaling pattern according to the setup channel and bit rate.
• In Sleep mode, the device detects wakeup messages.
• Detects Interference signals.
Note: After transmission, it takes duration of 2 bits before the device starts to listen to the DC-line.
4.2 Control Registers
4.2.1 Device operating parameters and statuses
The internal control registers shown in table 4.1 contain the device parameters and statuses:
Register 0
7
6
5
4
3
2
1
Interference
Sleep (“0”)
Register 1
7
6
5
4
3
2
1
“1”
“1”
Bit rate
Select frequency (table 4.2)
0
~F0/F1
0
Address
0[0]
0[1]
0[3:2]
Register Name
F1/~F0
Remote loopback
For future use
Table 4.1 - Device Control Registers
dir bits
Description
R/W 1 1 = F1, 0 = F0.
R/W 1 Transmits back the last received byte
Default
F0
0
00
@ 2007 Yamar Electronics Ltd.
7
DS-SIG40 R1.8