Stamp suggestions needed

Archiver

I'm new to microcontrollers. I am in need of suggestions. I wish to
use one of the many models of Stamp controllers to interface to a high
current linear DC power supply. I wish to use a 12-button keypad
matrix to punch in correct 4 to 6 digit code to activate 2 (K1 & K2)
relays. These 2 relays to remain energized until I type in a 2 to 3
digit OFF code. Also I need a short (1 to 5 second adjustable) delay
from K1 & K2 energized until another relay (K3) is energized. K3 to
remain energized until I type in 2 or 3 digit OFF code as well. K1,
K2 and K3 would all de-energize at the same time. Also wish to use 1
or more (prefer up to 6, if needed) temperature sensors to monitor for
excessive heat rise. If excess heat, then to activate 1 or more 12VDC
fans to cool things down. Also wish to monitor fans for locked fan
rotor using fan RPM lead. If 1 or more fans RPM leads indicated
locked rotor, then need to turn on an LED and buzzer alarm (with
manual way to silence buzzer only). Also wish fans to continue
running if need be (until temp. falls to below setpoint) even if I
type in 2 to 3 digit OFF code. I will have a ALWAYS ON Regulated
+12.0VDC source for this circuit as well as for the fans and relays.

Do you have any ideas or suggestions? The circuit and Stamp would
need to operate reliably in the presence of RF and at an ambient
temperature of upto and including 50 degrees C (122 degrees F).

Thanks…mwh87120

Archiver

In a message dated 6/30/2004 8:26:17 AM Eastern Daylight Time,
mwh87120@y... writes:


> I'm new to microcontrollers. I am in need of suggestions. I wish to
> use one of the many models of Stamp controllers to interface to a high
> current linear DC power supply. I wish to use a 12-button keypad
> matrix to punch in correct 4 to 6 digit code to activate 2 (K1 & K2)
> relays. These 2 relays to remain energized until I type in a 2 to 3
> digit OFF code. Also I need a short (1 to 5 second adjustable) delay
> from K1 & K2 energized until another relay (K3) is energized. K3 to
> remain energized until I type in 2 or 3 digit OFF code as well. K1,
> K2 and K3 would all de-energize at the same time. Also wish to use 1
> or more (prefer up to 6, if needed) temperature sensors to monitor for
> excessive heat rise. If excess heat, then to activate 1 or more 12VDC
> fans to cool things down. Also wish to monitor fans for locked fan
> rotor using fan RPM lead. If 1 or more fans RPM leads indicated
> locked rotor, then need to turn on an LED and buzzer alarm (with
> manual way to silence buzzer only). Also wish fans to continue
> running if need be (until temp. falls to below setpoint) even if I
> type in 2 to 3 digit OFF code. I will have a ALWAYS ON Regulated
> +12.0VDC source for this circuit as well as for the fans and relays.
>
> Do you have any ideas or suggestions? The circuit and Stamp would
> need to operate reliably in the presence of RF and at an ambient
> temperature of upto and including 50 degrees C (122 degrees F).
>

First of all, most of the Stamps have 16 I/O ports except for the BS2P40.
Your outline would require 7 ports for the matrix and 6 more for the sensors,
which leaves you with only 3 ports to do everything else. Review your
requirements carefully to make sure you need what you are asking for.

Also, you want to punch in a 4 to 6 digit code - this could get a bit
cumbersome. Using and 74HC595 shift register - or a TPIC6595 - you can get an 8-bit
output with a single byte control input. In effect this gives you control
numbers from 0 to 255 which can be used to control relays, fans or whatever.

Sid


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

First off, you are picking a heavy task to start off into
microcontrollers but the Stamp is a good first choice.
For the key matrix you can get by with 6 pins using readily available
keyboard encoders. There are even some available that comunicate
serially.
The relays and fans can be controlled using a shift register and then
appropriate driver devices. The shift register will reduce the number
of pins there.
You didn't mention what type of temp. sensor you will be using. If
they have analog outputs, there are many sources for 8 channel ADC's
with serial communications.
Some of the lines you use to talk to the shift register could be
shared with the ADC.
Now for the fans. If you wanted to use the Stamp for detecting each
fan individually, you'd need a seperate pin for each fan. Instead you
could use a 555 timer as a missing pulse detector for each fan and OR
the outputs together. That way the Stamp wouldn't know which fan was
bad but at least there would be an indication.

Lee

--- In basicstamps@yahoogroups.com, "mwh87120" <mwh87120@y...> wrote:
> I'm new to microcontrollers. I am in need of suggestions. I wish
to
> use one of the many models of Stamp controllers to interface to a
high
> current linear DC power supply. I wish to use a 12-button keypad
> matrix to punch in correct 4 to 6 digit code to activate 2 (K1 & K2)
> relays. These 2 relays to remain energized until I type in a 2 to 3
> digit OFF code. Also I need a short (1 to 5 second adjustable)
delay
> from K1 & K2 energized until another relay (K3) is energized. K3 to
> remain energized until I type in 2 or 3 digit OFF code as well. K1,
> K2 and K3 would all de-energize at the same time. Also wish to use
1
> or more (prefer up to 6, if needed) temperature sensors to monitor
for
> excessive heat rise. If excess heat, then to activate 1 or more
12VDC
> fans to cool things down. Also wish to monitor fans for locked fan
> rotor using fan RPM lead. If 1 or more fans RPM leads indicated
> locked rotor, then need to turn on an LED and buzzer alarm (with
> manual way to silence buzzer only). Also wish fans to continue
> running if need be (until temp. falls to below setpoint) even if I
> type in 2 to 3 digit OFF code. I will have a ALWAYS ON Regulated
> +12.0VDC source for this circuit as well as for the fans and
relays.
>
> Do you have any ideas or suggestions? The circuit and Stamp would
> need to operate reliably in the presence of RF and at an ambient
> temperature of upto and including 50 degrees C (122 degrees F).
>
> Thanks�mwh87120