CP3BT23_14 Datasheet, PDF (123/324 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

CP3BT23
www.ti.com
SNOSCX3A – JULY 2013 – REVISED JANUARY 2014
• Push-pull capability of the input/output pins
• Diagnostic functions
– Error identification
– Loopback and listen-only features for test and initialization purposes
18.1 FUNCTIONAL DESCRIPTION
As shown in Figure 18-1, each CAN module consists of three blocks: the CAN core, interface
management, and a dualported RAM containing the message buffers.
There are two dedicated device pins for each CAN interface, CANnTX as the transmit output and
CANnRX as the receive input.
The CAN core implements the basic CAN protocol features such as bit-stuffing, CRC calculation/checking,
and error management. It controls the transceiver logic and creates error signals according to the bus
rules. In addition, it converts the data stream from the CPU (parallel data) to the serial CAN bus data.
The interface management block is divided into the register block and the interface management
processor. The register block provides the CAN interface with control information from the CPU and
provides the CPU with status information from the CAN module. Additionally, it generates the interrupt to
the CPU.
The interface management processor is a state machine executing the CPU’s transmission and reception
commands and controlling the data transfer between several message buffers and the RX/TX shift
registers.
15 message buffers are memory mapped into RAM to transmit and receive data through the CAN bus.
Eight 16-bit registers belong to each buffer. One of the registers contains control and status information
about the message buffer configuration and the current state of the buffer. The other registers are used for
the message identifier, a maximum of up to eight data bytes, and the time stamp information. During the
receive process, the incoming message will be stored in a hidden receive buffer until the message is valid.
Then, the buffer contents will be copied into the first message buffer which accepts the ID of the received
message.
Figure 18-1. CAN Block Diagram
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CAN Module 123