The Pololu USB to RS232 converter is based on the Silicon Labs CP2102 chip. The data sheet and drivers for Mac and Linux (available real soon now from Pololu) may be downloaded from SiLabs site. For the data sheet see:
silabs.com/public/documents/ … cp2102.pdf
You can also download a program from SiLabs that sets various chip parameters like its power draw, product string, etc. into the eprom. See
silabs.com/tgwWebApp/public/ … erface.htm
The Pololu adapter works fine, but the CP2103 chip probably would have been a better choice as it offers 4 extra general purpose data lines. A similar chip from FTDI, the FT232R, already allows this and USB-RS232 adapters using this chip are available from competing robotics suppliers for a price similar to the Pololu unit. Furthermore, the actual functions of the various control lines of FT232R can be reprogrammed by free, downloadable software.
In connecting the USB adapter to the Baby O, I did experience a reset problem. When the Baby O is off, TX from the USB adapter will power it up weakly through the input protection diodes on PD0 (RX). This was solved by using a 1N4148 diode to block DC from the USB adapter TX, together with a 150K pullup resistor (may not be necessary) to +5 on PD0. With the connection working, I produced a skeleton of a simple command interpreter that allows one to talk to the Baby O through a USB port. See below for links to the code.
More recently, I’ve expanded the command interpreter to implement a 4 channel (3 are implemented) interrupt-driven serial servo controller for a robotics application. Simple commands given over the serial line, such as “F 150”, set the F servo to maintain a neutral position.
Let’s encourage Pololu to try to keep ahead of the pack, and especially, to inform their customers about the availability of software and drivers for their products.
Cheers, Jim
Links to the code for the skeleton of a command intepreter, based on the “stdio” example distributed with WinAVR follows.
You’ll need (servo_control.c or command_I.c) plus uart.c and uart.h
uoxray.uoregon.edu/orangutan/servo_control.c
uoxray.uoregon.edu/orangutan/command_I.c
uoxray.uoregon.edu/orangutan/uart.c
uoxray.uoregon.edu/orangutan/uart.h