Please explain LIN Parameter, bit quantization.

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naseeam

Joined Jan 4, 2017
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Please explain LIN Parameter, bit quantization. | Experts Exchange
We are using number of Local Interconnect Network(LIN) channels from Renesas RH850 / U2A16 Microcontroller in our embedded system. All LIN channels in our embedded system are Master.

What is LIN Parameter called bit quantization? I didn't find explanation of this parameter in LIN Controller user's manual.
 

Papabravo

Joined Feb 24, 2006
16,105
Bit quantization refers to dividing up each bit cell into an integer number of time quanta derived from a high frequency clock. When communicating on a non-synchronous network receivers must be able to adjust the point in the bit cell where they sample the data if their high speed clocks are running faster or slower than the master clock. Each side synchronizes at the beginning of a frame and can make small adjustments over the course of the frame. Each node on a LIN network must agree a priori what the bit rate should be. It is possible to have different frequency clocks, but the bit timing parameters must be adjusted to provide some measure of compatibility.

Disclaimer. I have not worked with an actual LIN network, but it is based on CAN with which I am intimately familiar.

This is how a slave device determines the baudrate.

SYNC: The SYNC is a standard data format byte with a value of hexadecimal 0x55. LIN slaves running on RC oscillator will use the distance between a fixed amount of rising and falling edges to measure the current bit time on the bus (the master's time normal) and to recalculate the internal baud rate.

Like with all such schemes the length of the frame must be limited to allow for the drift of clocks.
Refer to the following article:
Local Interconnect Network - Wikipedia
 
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