Communication

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Overview

Communication blocks provide serial interfaces for data exchange, sensor connectivity, and network integration. The MPLAB Blockset offers comprehensive support for UART (asynchronous serial), SPI (high-speed synchronous), I2C (multi-master bus), and CAN (automotive/industrial networking) protocols across all Microchip device families.

UART Blocks - Asynchronous Serial Communication

UART Config - UART Configuration and Initialization

All Families

UART peripheral configuration block that initializes baud rate, parity, stop bits, and hardware flow control. - **Baud Rate Configuration**: Automatic calculation from system clock

UART Tx - UART Transmit

All Families

UART transmit block for sending data via UART peripheral with automatic buffering. - **Byte and Array Transmission**: Single bytes or data arrays

UART Rx - UART Receive

All Families

UART receive block for receiving data with automatic buffering and error detection. - **Automatic Reception**: Interrupt-driven data capture

UART TxMatlab - UART Transmit to MATLAB

All Families

Specialized UART block for real-time data logging to MATLAB using picgui graphical interface. - **Real-Time Plotting**: Stream data directly to MATLAB GUI

UART Break and Autobaud - UART Break Detection and Auto-Baud

All Families

Advanced UART features for break signal generation/detection and automatic baud rate detection. - **Break Signal Generation**: Generate break condition (13 or 14 bits)

SPI Blocks - Synchronous Serial Interface

SPI - SPI Master/Slave

All Families

High-speed SPI communication block for interfacing with sensors, displays, and external peripherals. - **Master/Slave Mode**: Configurable role

I2C Blocks - Multi-Master Bus

I2C Master - I2C Master Controller

dsPIC33F dsPIC33E dsPIC33C PIC32 SAM

I2C master controller for multi-device bus communication with automatic protocol handling. - **7-bit and 10-bit Addressing**: Standard and extended addressing

CAN Blocks - Controller Area Network

CAN Config - CAN Configuration

dsPIC33F dsPIC33E dsPIC33C PIC32 SAM

CAN bus configuration block that initializes bit timing, filters, and message buffers. - **CAN 2.0A/B Support**: Standard and extended identifiers

CAN Tx - CAN Transmit

dsPIC33F dsPIC33E dsPIC33C PIC32 SAM

CAN message transmission block for sending standard or extended CAN frames. - **Standard/Extended IDs**: 11-bit or 29-bit identifiers

CAN Rx - CAN Receive

dsPIC33F dsPIC33E dsPIC33C PIC32 SAM

CAN message reception block with automatic filtering and interrupt-driven reception. - **Message Filtering**: Hardware acceptance filters (mask/match)

Block Selection Guide

By Communication Protocol

By Application Requirements

By Device Family Capabilities

Note: Actual peripheral count is device-dependent. Consult datasheet for exact numbers.

Device Family Support Summary

Legend: ✅ Full Support | ❌ Not Available

Notes:

• I2C: dsPIC30F uses different peripheral register structure, I2C_Master block designed for newer families
• CAN: PIC24 devices typically lack CAN peripheral; SAM devices support CAN FD (MCAN)
• Actual peripheral count varies by device. Consult datasheet for specific availability.

Protocol Comparison

Speed vs. Complexity

Troubleshooting Common Issues

UART

Problem: No data received

• Check: Baud rate matches on both sides
• Check: TX/RX pins not swapped
• Check: Ground connection between devices

Problem: Corrupted data

• Check: Baud rate tolerance (< 2% error)
• Check: Cable length (< 15 m for high speeds)
• Check: Electrical noise (use shielded cable if needed)

SPI

Problem: No communication

• Check: SPI mode (CPOL/CPHA) matches slave device
• Check: Clock speed within slave specifications
• Check: CS signal active during transaction

Problem: Data corruption

• Check: Clock speed not too fast for slave
• Check: Ground connection between master and slave
• Check: Cable length (keep short, < 1 m for high speeds)

I2C

Problem: No acknowledgment from slave

• Check: Pull-up resistors on SDA/SCL (typically 2.2 kΩ - 10 kΩ)
• Check: Correct slave address (7-bit vs. 8-bit notation)
• Check: Slave device powered and ready

Problem: Bus hangs or clock stretching

• Check: Slave device not stuck (power cycle)
• Check: Timeout settings in master
• Check: Bus capacitance (shorter wires, fewer devices)

CAN

Problem: No messages received

• Check: Bit rate matches network
• Check: Termination resistors (120Ω at both ends)
• Check: CAN_H and CAN_L not swapped
• Check: Message filters configured correctly

Problem: Bus errors

• Check: Electrical noise (use proper CAN cabling)
• Check: Ground loops (ensure common ground)
• Check: Maximum bus length not exceeded (40 m @ 1 Mbps)

See Also

Related Block Categories:

• Digital I/O Blocks - For GPIO chip select and control signals
• Timer Blocks - For communication timing and timeouts
• DMA Blocks - For high-speed data transfer

Application Notes:

• AN1045 - Implementing a UART Bootloader in Software
• AN1088 - CAN Bus Application Design
• AN754 - Implementing I2C Multi-Master Mode

Example Projects:

• Communication Examples - UART, SPI, I2C, CAN demos
• Board Templates - Pre-configured communication interfaces

💡 Quick Selection Guide:

• Need point-to-point communication? → UART
• Need high-speed data transfer? → SPI
• Need multiple sensors on 2 wires? → I2C
• Need robust automotive/industrial network? → CAN
• Need MATLAB real-time logging? → UART_TxMatlab