Here’s an easy way to add more serial ports via I2C:
I got the wrong crystal size, so it’s mounted a bit awkwardly:
There are two jumpers, allowing up to 4 serial ports to be added to each I2C bus – i.e. up to 16 on the bit-banged I2C buses, and 4 more on the hardware I2C line. Since the A0/A1 jumpers actually support up to 16 addresses with a bit of extra wiring, you could theoretically connect up to 80 serial ports to a single JeeNode!
Here’s some sample code:
It sets the serial port to 57600, 8 bits, no parity and then sends whatever comes in to the “normal” serial port. The default fast I2C bus rate of over 1 Mhz appears to work just fine.
The header of the UART plug is compatible with FTDI, so you can hook up another JeeNode to it:
In this case, I used a JeeNode with a room plug prototype. Sample output:
This demo code has been added as “uart_demo” example in the Ports library and is also available here.