Saturday, April 18, 2009


I just got my MAX233A samples from Maxim. They’re UART RS232 <—> TTL level computers so you can interface your PIC’s UART to your computer’s RS232 port. Makes development a lot quicker since it’s easy to program and view output.

On windows, you can use the termite terminal to communicate via UART on a windows machine. On a Linux machine, you have a lot more options – see Minicom. There are even floppy Linux distributions designed just for this purpose, so you can pull that old 386 out and put it to some use.

The great thing about the MAX233A is that it requires no external capacitors for its internal charge pumps (which are used to boost voltage levels to RS232 specifications). The only thing that’s required is a decoupling capacitor as described in the sample circuit in the datasheet.

I salvaged an old RS232 mouse for its cable. It had all the wires I needed (TX, RX, GND) to fully interface to my microcontroller.

So just go ahead and order some samples of the MAX233A – it’s a great little chip.

If you have a PIC that supports self writes to flash, you can even write (or download) a serial bootloader and development will go even faster as you’ll be able to program your chip directly over UART.

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