UART Baud Rate Frequency Shifting to Reduce Radio Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern electronic devices with UARTs face interference issues with on-die radios due to shared communication frequencies, leading to performance degradation and increased complexity and cost when trying to mitigate these interferences.
Innovation Solution
A system with a UART configured to shift its baud rate so that it is not evenly divisible by the radio's operating frequency, using a baud clock generator with frequency shift dividers to generate an operating baud rate that minimizes interference with radio signals, allowing transmitter and receiver circuitry to operate effectively without disrupting analog signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If UART operates at a fixed baud rate that is evenly divisible by the radio operating frequency, then synchronization is simplified, but interference with radio signals increases
Solution Approach 1:
The patent changes the baud rate parameter from a fixed value to a dynamically adjusted value. The slave UART modifies its baud rate slightly (e.g., from 19200 to 19201 or 19199) to ensure it is not evenly divisible by the radio operating frequency, thereby eliminating harmonic interference while maintaining communication functionality.
2Reliability
If all UARTs cooperate to reduce interference, then radio performance is improved, but device complexity increases
Solution Approach 1:
The slave UART autonomously adjusts its own baud rate based on local detection of the radio operating frequency. Instead of requiring coordination with other UARTs or central control, each slave UART independently modifies its baud rate to avoid interference, simplifying the overall system architecture.
Solution Approach 2:
The system implements a feedback mechanism where the slave UART detects the radio operating frequency and uses this information to adjust its baud rate. The adjustment amount is calculated based on the detected frequency, creating a closed-loop system that automatically eliminates interference.
3Object-affected harmful factors
If baud rate is shifted to avoid even divisibility, then radio interference is reduced, but communication precision may be affected
Solution Approach 1:
The patent applies a small, controlled adjustment to the baud rate (typically ±1 from the nominal value) rather than a large change. This partial action is sufficient to break the even divisibility relationship and eliminate harmonic interference, while being small enough to maintain acceptable communication accuracy and synchronization.
Data Source
AI summary
An electronic device includes a radio configured to operate at an operating frequency, and a first universal asynchronous receiver/transmitter (UART) configured to operate as a master and at a baud rate. The electronic device also includes a second UART configured to communicate with the first UART, operating as a slave. The second UART has a controller configured to generate a frequency shift based upon the operating frequency of the radio being evenly divisible by the baud rate, and a baud clock generator. The baud clock generator is configured to generate an operating baud rate from a master clock signal, with the operating baud rate to be the baud rate shifted by the frequency shift. Transmitter circuitry is configured to operate based on the operating baud rate, and receiver circuitry is configured to operate based on the operating baud rate.