In embedded systems, the Timer is a critical peripheral module. It not only enables precise delays but also generates Pulse Width Modulation (PWM) signals, captures external events, and executes periodic tasks.
We previously covered the basics of timers in Fundamental Knowledge of Timers in Microcontrollers: An Introductory Guide. In this article, we’ll go over the TCA timer module, using AVR microcontrollers as an example.
1. Basic Concepts of Timers
To refresh: a timer is a hardware module designed to count clock pulses or external signals for time control. Unlike software-based delays, hardware timers offer higher precision and lower CPU load.
2. TCA Timer Mode Overview
Using AVR® microcontrollers as an example, we introduce a common timer mode:
TCA Timer Mode
The TCA Timer is an optimized timer for generating PWM signals, available in devices such as:
Figure 1: TCA Timer Functional Block Diagram
The module can operate in 16-bit mode for high-resolution output or split into two independent 8-bit modes. The timer runs continuously until it reaches the TOP value. At TOP, it resets to BOTTOM (zero), except in dual-slope mode, where it counts down to zero instead:
Figure 2: TCA Timer Operation Modes
To generate PWM signals, TCA uses comparison channels to check if the timer value matches or exceeds a setpoint. If so, the corresponding output goes high. The timer also supports double buffering, where written values are stored until the device receives an update trigger (mode-dependent). Advanced control is possible via the Event System (EVSYS), which can gate inputs, count event edges, control count direction (up/down), and restart the timer under various conditions.
Follow for more information on timer modules in our next post: Introduction to AVR Microcontroller Timer TCD Modes
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