UART Config Block

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UART_Config Block The UART Config block configures a UART (Universal Asynchronous Receiver/Transmitter) module for serial communication. This block sets up baud rate, pin assignments, operating modes, and implementation methods for both transmit and receive operations.

Block Inputs/Outputs

Inputs: None (configuration block only)

Outputs: None (configuration block only)

This is a configuration block that sets up UART peripheral parameters. It does not have signal ports—use UART Tx and UART Rx blocks for data transmission and reception.

Supported Device Families

Family	Series	Architecture ID	Notes
dsPIC	30F, 24F, 33F, 33E, 33C, 33A	1, 2, 3, 4, 8	Full support including IrDA on capable devices
PIC32	MK, MZ, MX, PIC32A	Included in dsPIC arch	Standard UART functionality
SAM	E7x, E5x, D5x, C2x, D2x	5, 6, 7	USART peripheral (SAMx callback variants)

Block Parameters

UART Selection

Parameter	Description
UART Module	Select UART/USART number (1 to N, depending on device)

Number of available UARTs detected automatically from selected chip.

Baud Rate Configuration

Parameter	Options	Description
Baud Rate Selection	Popup list or Custom	Choose from standard rates (110 to 12M baud) or enter custom value
Standard Rates	110, 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, …	Up to 12000000 baud on capable devices
Custom Baud	User-defined	Enter any baud rate value (validated against FCY)
Init Sequence Baud	Same options	Optional different baud rate for initialization sequence

Operating Modes

Mode	Description	Availability
Full Duplex	Default mode - independent Tx and Rx	All devices
Half Duplex	One-wire Rx-Tx (shared pin)	All devices
IrDA Mode	Infrared communication (requires IrDA encoder/decoder)	Only on devices with UxMODE bit 12

Transmit (Tx) Implementation

Mode	Description	Use Case
Do not implement Tx	No transmit capability	Receive-only applications
Simplest	1, 4, or 8 byte internal buffer (device dependent)	Low data rate, minimal overhead
Circular Buffer	Software circular buffer with interrupt	Moderate data rate, reliable
DMA Ping-Pong	Two DMA buffers alternating	High throughput, no data loss
DMA Circular Buffer	DMA with circular buffer	Continuous streaming
DMA Single Buffer	Single DMA buffer (possible data loss)	High speed, can tolerate data loss

Receive (Rx) Implementation

Mode	Description	Use Case
Do not implement Rx	No receive capability	Transmit-only applications
Simplest	1, 4, or 8 byte internal buffer	Low data rate polling
Circular Buffer	Software circular buffer with interrupt	Reliable reception, moderate rate
DMA Ping-Pong	Two DMA buffers alternating	High throughput reception

Pin Configuration

Parameter	Description
RX Pin	Receive data pin (remappable on PPS-capable devices)
TX Pin	Transmit data pin (remappable on PPS-capable devices)
CTS Pin	Clear To Send (hardware flow control, optional)
RTS Pin	Request To Send (hardware flow control, optional)
DTR Pin	Data Terminal Ready (dsPIC CK/33A only)
DSR Pin	Data Set Ready (dsPIC CK/33A only)

Advanced Options

Parameter	Description
Idle Time Control	Insert phantom bytes for idle time on Tx line (dsPIC CK only)
Initialization Sequence	Configure different settings at startup
External PIL Communication	Enable for Processor-in-the-Loop testing

Registers Configured

dsPIC/PIC32 Registers

**``**``**``**``**``**

Register	Description	Configured Fields
U	x	BRG
U	x	MODE
U	x	STA
U	x	BRGH
U	x	MODEH
U	x	STAH

SAM Registers (USART)

SAM devices use USART peripheral with different register structure:

US_CR - Control Register
US_MR - Mode Register
US_BRGR - Baud Rate Generator
US_IER/IDR - Interrupt Enable/Disable

Usage Example

Basic UART Setup (9600 baud, Full Duplex)

Add UART Config block to model
Configure parameters:
UART Module: 1
Baud Rate: 9600
Duplex Mode: Full duplex
Tx Implementation: Circular Buffer
Rx Implementation: Circular Buffer
RX Pin: Select from dropdown (e.g., RP36/RB4)
TX Pin: Select from dropdown (e.g., RP37/RB5)
Add UART Tx block (same UART number)
Add UART Rx block (same UART number)
Build and deploy

High-Speed UART with DMA (115200 baud)

Configure UART Config block:
Baud Rate: 115200
Tx Implementation: DMA Ping-Pong Mode
Rx Implementation: DMA Ping-Pong
Ensure DMA channels are available on selected device
Configure buffer sizes in Tx/Rx blocks

Implementation Details

Baud Rate Calculation

For dsPIC/PIC32 devices: UxBRG = (FCY / (4 * BaudRate)) - 1 (BRGH = 1) UxBRG = (FCY / (16 * BaudRate)) - 1 (BRGH = 0) The block automatically selects BRGH mode for best accuracy.

Buffer Management

Circular Buffer: Size configurable in Tx/Rx blocks, uses interrupts
DMA: Requires DMA-capable device, minimal CPU overhead
Ping-Pong: Two buffers alternate, prevents data loss during buffer swap

[UART Tx] - Transmit data
[UART Rx] - Receive data
[UART TxMatlab] - MATLAB interface for testing
[UART Brk/Autobaud] - Break detection and autobaud

Troubleshooting

Baud Rate Error Too High

Problem: Desired baud rate cannot be achieved with acceptable error.Solution: Adjust system clock (FCY) or choose a different baud rate that divides evenly.

Pin Not Available

Problem: Selected pin not available for UART function.Solution: Check device datasheet for UART pin mapping. Ensure PPS is configured correctly on remappable devices.

DMA Not Working

Problem: DMA mode selected but not functioning.Solution: Verify device has DMA capability. Check DMA channel availability in model (other blocks may use DMA).