Serial shield


I want to build a "hardcore" serial shield. Faster than the software implementation, with hardware handshake. I will try to work with the MAX3110E, communicating via SPI and probably use one DB9 socket on a protoshield.

It looks deceptively simple. Connect 5V, GND and pins 10-13 for SPI. Add a quartz, two small capacitors, a DB9 socket and you are done.

But if it is so simple, why hasn't it been done before? Or has it?

Best, Jens

I started down this route, and realized that I could do the same thing with another ATmega as the SPI (or I2C) UART peripheral for about half the cost of the 3110E, and I already had ATmegas, crystals, etc lying around. The 3110 has an 8 or 16 byte buffer, I could have nearly 1K for the buffer with an ATmega. Plus I could do things like use it to interface with a serial GPS, preprocess the data, and effectively have an I2C GPS.

Having said all that, here’s an eagle design for a MAX3110 shield. I think I have a single sided prototype (without the interrupt line, IIRC) around somewhere. I built the hardware, and got lazy before I deciphered the datasheet and wrote the software.


Woohooo!!! Thanks a lot!

(Hmm... I still have the 168 left over from upgrading to the 368....)

Best, Jens