Bit level timing calculator GUI for CAN/CANFD
F_in: given input clock frequency of the CAN protocol controller Prescaler: scales down the input clock for the internal time base:
TimeQuantum = 1/F_in * Prescaler
e.g.:
F_in = 80 MHz
Prescaler = 8
TimeQuantum = 1/80000000*8 = 0.0000001 s = 100 ns
Bit Time: Each bit is divided into 4 segments:
<---------------- T_bit ------------------->
--------------------------------------------
| SYNC | PROP | PHASE1 ! PHASE2 |
--------------------------------------------
<-------TSEG1---------><--TSEG2-->
<-SJW->
SYNC: Synchronization segment
always 1 TimeQuantum long by the CAN standard
PROP: Propagation segment
PHASE1: Phase segment1
PHASE2: Phase segment2
!: Sample point: always at the end of Phase segment 1. Can be expressed as a
position in the BitTime in percentage.
TSEG1: Time segment 1: usually this can be configured in a CAN controller
minimum 1 TimeQuantum long
TSEG2: Time segment 2: usually this can be configured in a CAN controller
minimum 1 TimeQuantum long
SJW: (Re)Synchronization Jump Width: The controller can lengthen TSEG1 or
shorten TSEG2 by this value at resynchronization.
TimeQuanta/BitTime: The number of TimeQuanta in a bit time:
TQ/BT = SYNC TSEG1 TSEG2 = 1 TSEG1 TSEG2
SamplePoint: Position of the sample point in the bit time in percentage:
SP = (SYNC TSEG1) / TQ/BT * 100 %
BaudRate: Comes from the TimeQuantum, and the TQ/BT
1
BaudRate = ---------------------
TimeQuantum * TQ/BT
So with the wbove example and with TSEG1 = 15 and TSEG2 = 4:
TQ/BT = 1 15 4 = 20
BaudRate = 1 / (20 * 100ns) = 500000 = 500 kbps
SamplePoint = (1 15) / 20 * 100% = 80%
In this folder, create a new virtual environment, activate it, and install the dependencies:
> python -m venv venv
> .\vent\Script\activate
(venv) > python -m pip install -r requirements.txtCall the module from the virtual environment:
(venv) > python -m can_bit_timing_calculator