1 tq
1 tq
1 tq
1 tq
1 tq
1 tq
1 tq
1 tq
1 tq
1 tq
Nominal Bit Time
(Single CAN bit)
Sync
Phase 1
Phase 2
Prop
Sample Point
Firmware
14
SLLU216 – July 2019
Copyright © 2019, Texas Instruments Incorporated
SPI to CAN FD SBC + LIN Transceiver BoosterPack User's Guide
2.4.10
TLIN2029-Q1 Enable (EN)
EN controls the operational modes of the device. When EN is high the device is in normal operating mode
allowing a transmission path from TXD to LIN and from LIN to RXD. When EN is low the device is put into
sleep mode and there are no transmission paths available. The device can enter normal mode only after
wake up. EN has an internal pull-down resistor to ensure the device remains in low power mode even if
EN floats.
3
Firmware
The TCAN4550-Q1 CAN FD controller with integrated transceiver SBC supports classic CAN and CAN FD
communication through a SPI interface and incorporates the common Bosch_M_CAN controller. The
provided firmware examples helps users configure their MCU for CAN or CAN FD communication without
a deep understanding of the CAN/CAN FD protocol. A basic overview of the firmware features is included
in this document, but a more detailed explanation can be found in the
TCAN45xx software user's guide
3.1
CAN / CAN FD Controller Configuration
The CAN controller is a state machine that manages protocol-specific details leaving the microcontroller to
focus on managing the data being transmitted and received. These details must be setup during
initialization of the TCAN4550-Q1 following every power cycle and reset event. Several of these settings
are critical to proper communication and varies in value based on factors such as data rate, crystal
oscillator or clock frequency, and physical bus characteristics that may lead to adjustments in the proper
sample point within the bit period to avoid noise and overshoot ringing that needs to settle out before
sampling the bit and avoid errors.
3.1.1
Bit Timing Setup
Figure 7. Nominal bit time
There are 4 sections to a nominal bit time in the CAN protocol: the synchronization segment, the
propagation delay time segment, and the phase buffer segments 1 and 2. The sync_seg is used to
synchronize the nodes in the network. The prop_seg is used to compensate for any physical delay times
in the network and must be long enough to compensate for the delays between the sender and receiver
and back to the receiver again in order to allow for successful arbitration. The phase_seg1 and
phase_seg2 are used to compensate for signal edge phase errors and is adjusted based upon the
sync_seg to adjust the bit's sample point which occurs between the phase_seg1 and phase_seg2.
