Keeping to some decisions

Well, been thinking about a few things. Was extremely tempted to use a complex motor driver board, lots of sensors(even figured out how to read them*at least in theory*), and thought about just scrapping the present body for a bigger and better bot body. All great and wonderful ideas, but one thought kept popping up, I've not even really started my first bot, so there is nothing to improve on, yet.

Going to use the AtMega 328 for the controller still, yes there are more powerful MCUs out there, but I think to monitor 3 bumper switches, 5 IR range sensor, controlling 2 geared down DC motors, monitor 2 drive encoders and monitor the drive batteries that it is still overkill. With 14 I/O pins and 6 analog pins, 30k of memory(ty for the chip upgrade at adafruit.com).

The dozer body is small, but has enough room to hold the 4 AA batteries for the motors, a 9v battery for the MCU and sensors, the L293D with it's heatsinks and the AtMega328 after the modifications.

The motors that came with the dozer body are adequate in power to push the dozer body about, but not able to slam it into walls and furniture at high speed(under powered is good safety feature at times). Yes, it's a bit underpowered, but if I'm going to change out the motors, it might be more feasible to just use a bigger bot body and maybe a different kind of drive.

The L293D chip is the best option as far as price, size and simplicity goes. Only need to drive 2 DC motors and it only requires 4 PWM pins from the AtMega328. Yes, could just cobble together a dual H-bridge using transistors and diodes, but why? It will cost a few bucks for the chips, the socket, a pc board, connectors and heatsinks and I don't have to debug it, so a total win win situation. Using just 4 digital pins with PWM.

As far as sensors go, I'm doing the sensors in stages and in baby steps. I'll start off with the bumper switches, yes mechanical switches are bouncy, but they are reliable for the most part and easy to read(on or off), so there goes 3 digital pins and 4 more digital pins for the motor control. Then will work on the battery monitor sensor, so then will be using 7 I/O pins and 1 analog pin. I should be ready to tackle the IR ranging task by then, which when completed I'll have used up 7 I/O pins and all 6 analog pins. So then I will have 6 digital I/O pins left to play with,unless I figure out how to read the IR sensors with just one analog pin.

So far:

AtMega 328 MCU
Still going to use the dozer body
Not going to change the motors out, yet
Using a L293D Chip to drive the motors
Sensors will be bumpers, IR modules, a digital compass and battery monitor

What would be dreamy:

A hover body with a minimum of 10lb payload
Networked ARM modules
SONAR and Sharp modules
Full Stereo Vision with object recognition
A fully articulated gripper and robot arm
Speech Recognition and Synthesis
Neural Network for complex decision processing

Reality as of now:

A not yet hacked dozer body (0%)
AtMega 328 that I'm still learning how to use(I can make the LED blink)(100%)
A not yet hacked mouse(0%)
A handful of lithium ion rechargeable batteries(50%, no 9v batteries yet)
A 9volt battery clip(50% to 100%, I've not decided if the board will have a backup PS)
No other sensors(0%)
Solderless Breadboard
Misc Discrete Components