Implementing Auto-Direction RS-485 in Smart Grid Telemetry: A COS13487 Study

Traditional half-duplex RS-485 nodes require a dedicated GPIO pin from the MCU to toggle the Driver Enable (DE) and Receiver Enable (/RE) lines. If a software glitch leaves the driver active, the entire bus can lock up. The COS13487EESA integrates an internal state machine that automatically detects transmit data activity and enables the driver, returning to receive mode when the write cycle finishes.

Reducing Firmwares Overhead

By removing the timing critical DE control from software, developers prevent communication conflicts and simplify the network protocol. The chip's failsafe feature guarantees a high output state if inputs are open-circuited.

• Baud Rate: 250 kbps maximum rate.
• Unit Load: 1/4 unit load allows up to 128 nodes.
• GPIO Savings: Saves 1 I/O control line per transceiver node.