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Middle section: B32, electronic compass, beeper, switches, connectors and misc. logic.
| The middle section holds most the
electronics logic. It is connected with the lower and upper levels with connectors. To connect the upper section I am using three DB9 connectors. The CPU (lower right in picture) is the 68HC912B32 (B32) that has built in 32kb flash memory, 1kb ram, 768 bytes eeprom, 8 channel 8 bit A/D, 4 pulse width modulation (PWM), timers, serial lines plus more. Lower right to the B32 is a button (looks like a red dot). This allows me to give input to program when it is running. Above the B32 in the picture is one of the DB9 connectors that connects the sonar pod to the B32. Next above that are the state switches. Setting those switches tell the B32 to either boot from flash, be in program mode, boot from eeprom or be in BDM mode. Next section are the transistors used to power the relays for the sonar pod (explained in the upper section). |
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| The wheel encoder logic is a LM339 to
interpret the logic levels of the wheel encoders. There are two on board regulators, 12V used for programming the flash. The 5V for miscellaneous 5V needs, but not the CPU which uses the four AA batteries. The Vector Compass board tells the robot what direction it is heading according to magnetic north. The last is the beeper to give audible feedback. It is a beeper hooked directly to the B32. There are several capacitors to keep power surges from effecting the B32. The whole thing is put on four breadboard connectors that are linked together. I started with three but needed more room. I love the breadboard approach, allows quick changes and experimenting. In future months I will write articles going into detail the various sub-systems. |