Need to buy new board?

Jugular

Hello,

I am not sure how to title this exactly so I went with this.

Anyway I have the Homework board and am wanting to program myself a single bs2 chip that I can put on my own pcb. Is there a way that I can send the program to the new bs2 with the HW board or do I need to go about this a different way? Or would buying a carrier board be the simplest?

Also one more question simplified as much as I can. I am wanting to buy a keypad, 4x20 display, two hall effect sensors and one LM34 temp sensor. I believe there will be enough I/O pins to cover all these devices. I am planning on trying to place these items on my scooter (yeah i know its lame, but I think it would be fun). Im newer with this stuff and since im not an electrical engineer (ME actually [noparse]:D[/noparse] ) I was wondering if the bs2 can handle the two hall sensors and a temp sensor(doesn't have to update the temp but every few seconds or so) as well as the keypad input and the lcd output at the same time? Or would it be best for me to try to go to the propeller chip for the extra processors?

Basic setup:
1 hall sensor to determine engine rpm
1 hall sensor to determine speed of scooter
1 temp sensor for either ambient or engine temp, haven't looked up operating temp of the scoot yet
1 keypad to work a relay for push button start of engine instead of key use
1 lcd display to show speed, rpm, and temp on screen all at same time

Am I asking too much from one chip? I don't believe I am, but please correct me on any anything you see that will lead me in the right direction.

Thank in advance!


*edited for typo*

Mike Green

A Hall-effect sensor puts out a pulse when a magnet goes past. You want to count the pulses over some period of time. One Hall-effect sensor takes one I/O pin and the Stamp will be busy during the counting interval which should be no more than a fraction of a second so the Stamp isn't tied up too long. You can measure the pulse rate once a second or so to update the speeds involved.

An LM34 sensor puts out a voltage proportional to the temperature. You have to convert this analog voltage to a digital value. It's usually best to use an external analog to digital (ADC) converter for this, something like an ADC0801 for a single channel or an ADC0804 for 4 channels. These would take 3 or 4 I/O pins per ADC.

An LCD display takes one I/O pin

A keypad could take quite a few I/O pins if the Stamp has to handle it. Consider using a MemKey keypad controller or an LCD that can handle a keypad as well. This would add one or two I/O pins with a MemKey or LCD controller.

Most products sold by Parallax have links on their webstore page to documentation and sample code. I suggest you check out Parallax's LCDs and MemKey keypad interface. There are plenty of examples of ADC080x ADC use between the StampWorks Manual and the Basic Analog and Digital tutorial and the Nuts and Volts Columns, all downloadable from Parallax (start with the Resources tab on the main Parallax webpage).

Jugular

You know what, I should have made myself a little more clear. I do have the 2 magnets offered by Parallax in my shopping cart as well as the MEMkey board. I did not remember about the ADC, as I have actually thought about getting one of the LM34's a while back so thank you for reminding me to check into that. I appreciate you linking me the ADC part numbers.

So with this project do you think it would be better for me to pick the lcd with the 4 push buttons on the bottom of it to switch between which sensor it is reading instead of trying to get each sensor to show on the bigger lcd at the same time?

And the last thing, can I program a new bs2 chip with the homework board I have on the breadboard part of it? I am a little confused about this part of it.

Mike Green

The circuitry needed for programming a Stamp module is given in the Stamp Manual on page 28. It's pretty simple and would indeed fit on the little breadboards that Parallax uses. I'd be careful about using a breadboard if you have to plug and unplug the Stamp a lot. That can wreck the pins.

There's no "best answer" for what you should use for a display. Either a 4x20 or a 2x16 backlit serial display would work very nicely and either would allow you to show 4 different values at the same time. For the 2x16 display, you'd have decals on the bezel around the display that would label the values shown. With the larger 4x20 display, you could include the labels as text on the display.

Jugular

Ahh ok, sorry my book is far away at the moment and I honestly didn't go through it page by page. I am sure I seen it, but must have forgot. I have a few extra blank boards around I can build the circuit on so I will not wear out the homework board needlessly.

I appreciate all the help and direction you have give me.