SparkFun RS232 Breakout

The SparkFun RS232 Breakout is a versatile utility board designed to seamlessly connect modern electronics with legacy RS232 serial devices. This board is ideal for bridging the gap between 3.3V microcontrollers and older devices using a DE9 connector, effortlessly converting low-voltage TTL logic to the higher-voltage RS232 standard.

The heart of this breakout is the ST3222 RS232 driver/transceiver from STMicroelectronics, which efficiently manages voltage-level shifting. It converts 3.3V logic signals to the ±5V (or higher) signals required by RS232 and vice versa. Operating at a power supply voltage between 3.0V and 3.6V, it is perfectly suited for 3.3V microcontrollers. With support for data rates up to 250Kbps, it easily handles most RS232 applications. Additionally, for battery-powered projects, the low-power shutdown mode reduces supply current to just 1mA, providing energy-efficient monitoring for device activity.

Simplicity is a core feature of this board. The female DE9 connector allows for direct connection of RS232 device cables, while the microcontroller pins are accessible via a standard 2.54mm-spaced, 9-pin plated through-hole header. This design eliminates the need for guessing with null-modem or crossover cables, as the board internally manages TX/RX signal crossover. Simply connect the TX and RX pins from the microcontroller to the breakout, and the board handles the rest. This feature simplifies wiring and troubleshooting, ensuring a hassle-free experience. Two mounting holes are also included, allowing secure installation in an enclosure or project.