Microcontroller
The following chart compares some basic features of some of the microcontrollers used in the club. Links to more data on some of the controllers are given after the chart.
|
|
Basic Stamp |
BX24 |
PIC |
68HC912B32 |
68HC11E1 |
|
Clock Speed |
20 MHz |
? MHz |
20 MHz |
8 MHz |
8 MHz |
|
EEPROM/Flash |
2K |
32K |
8K |
32K |
1/2K |
|
RAM |
32 |
400 |
368 |
1024 |
32K |
|
Memory Expansion? |
no |
no |
|
64K RAM |
64K |
|
Digital I/O |
16 general purpose I/O |
16 (less those used for analog) |
33 (less those used below?) |
63 (less those used below) |
21 (less those used below) |
|
Source/Sink current |
20/25 ma |
10/20 ma |
25/25 ma |
25/25 ma |
?/25 ma |
|
Analog input |
For resistive sensors 16bit |
8 chan |
8 chan 10 bit |
8 chan 8 bit |
8 chan 8 bit |
|
Inp/Out capt |
Input cap |
|
yes |
8: inpt cap or out comp |
4 inpt cap |
|
Pulse accum |
Yes |
|
no |
Yes |
Yes |
|
PWM channels |
Yes |
2 |
2 |
4 8bit/2 16bit |
4 16 bit |
|
Serial interface |
RS232 (up to 16) |
RS232/SPI or parallel |
RS232? External components? |
RS232/SPI |
RS232/SPI |
|
Real Time Intr |
no |
Yes?? |
Yes |
Yes |
Yes |
|
Other interrupts |
no |
|
14, |
2 external |
2 external |
|
Power req’mt |
5vdc or >8 |
4.8 to 15 vdc |
5 vdc +/- 10% |
5 vdc or > 8 |
5 vdc |
|
Programming |
Built-in Pbasic interpretor. |
|
Assembler |
Freeware: |
Freeware: |
|
Floating point math? |
No |
Yes |
Yes |
Yes..with Imagecraft C |
Yes, with Max-Forth & Img C |
|
Other features
|
Trig,log,exp,sqrt functions. Networks |
Multitasking |
RS485 |
Card inserts into standard protoboard |
Board has 2 H bridge drivers for robot wheels |
|
Price |
$50. |
$100 starter kit $50 chip |
$12. |
$120 starter kit |
$135 |
More data:
Basic Stamp 2: Manufacturer site is Parallax.com. Skip down to the BS2-IC part number and go back to their home page to find more info.
Jim Ubersetzig has sample software to perform many functions on the BS2, (including driving an Ebot). This alone is a good reason to go with the Basic Stamp. Click here for a list of software that he has available. A program to run Ebot can be found on the programming page.
Jim also supplied a schematic of how to hook up a BS2 to drive your robot. ALL the wiring required is given.
One disadvantage to the Basic Stamp is that it does not have interrupts. When we get to installing encoders on the wheels to measure distance traveled, the Stamp will have to read the encoders by polling very frequently to determine when the encoder pulses appear. This makes it difficult to get any other processing done. However, there is a simple hardware circuit available which can be added to eliminate this problem. The circuit is provided later.
PIC: Manufacturer data is available from www.microchips.com.
Support equipment including an In-Circuit programmer and PBasic compiler can be seen at microengineeringlabs.com/products/pbp.htm
68HC912B32: Click here for a description of the Adapt912 implementation of the 68HC912B32 by Technological arts.
