MultiSerial Shield

The Arduino MultiSerial shield will let the Arduino access a number (4 or 8 likely) of RS232 serial ports via SPI. It will have switchable TTL or RS232 levels. This project exists mainly as a debugging tool for networks of BlinkieBits, as (at least during BlinkieNet design/prototyping) it would be extremely useful to be able to receive debugging information from a whole network of BlinkieBits, rather than just one at a time.

• The MAX3110 chip would do everything we need in one chip, but is $11 per channel!
• The NXP SC16IS752 chip gives 2 channels for ~$7 but needs 3.3v I/O and talks 3.3v RS232. The PCA9306 chip will solve the former issue and is $0.95 qty. 1, and the latter issue will be solved with a second-sourced TI MAX3232 in a SOT16 package for $1.70 qty. 1.