opens up more possibilities for us looking at getting a more reliable control
over 1wire. Distribution of control via the AE in the BAE0910 will be
great. The weak link I have in my system is obviously the reliance of the
1wire master / script running in the host. It just so happens I am
currently building another automated aquarium for a small reef tank right
now. I thought if I explained the application after having a skim read of
capabilities of the BAE0910 you maybe able to comment on the
major advantage I see in 1wire over a PIC is the simple wiring and as such want
to try and keep the component count down and thus reliance on soldering
techniques. Don;t get me wrong I have built lots a of "bird nest" style
controllers in the past and studied electronics however I want to create
something that isn't too hard for anybody to build within the Aquarium
DIGITAL CONTROL OF RELAYS
Requirements: Generally the digital control is a
glorified light timer. Currently thoughts are to simply use "cron" to
start a simple 1 line script to open or close various relays
throughout the day. Typically require 8 or 12 relays however the relay
boards are in groups of 4. I use a futurlec board (US$15.00) 10Amp relays,
opto isolated and includes all pull up resistors etc etc. i.e. currently
use a DS2408 direct to relay board.
Possible enhancements using a BAE0910.
control. I would like to be able to use 4 push buttons and when pushed,
toggle the corresponding output. This means if the host is down I can
still walk up to the tank and manually control each output. I propose to
use 4 switches / resistor network in parallel on the ADC line so the wiring to
the push buttons is simplified. Thus the push buttons or host can control
the output. The only complication maybe that the host would set a
parameter to 0 or 1 for on/off and the push button is a momentary pulse that
needs to toggle the same parameter as the host.
Failsafe......A future enhancement, I would like to send a watchdog
pulse from the 1wire host to the BAE0910, say every minute. If the BAE0910
does not see this pulse (leading edge) in say ~30 minutes, it assumes the host
is down and the outputs go to a pre-configured failsafe position for each of the
four outputs. In this mode the push buttons would work as normal and just
toggle the corresponding output, manual control. When the host is back,
watchdog is sensed, the outputs simply stay at there current position
waiting for host control if required, which is called bumpless
output....In one case I want to turn a pump off when feeding the fish.
That means from a push button I want to control an output and turn it off for
say 15 minutes when the leading edge of the button is
the above feasible ?
I have 1 ADC and 4 DO
Requirements: To control the temperature of the aquarium.
A heater with inbuilt thermostat is used coupled with a Fan for cooling.
On a hot day you can get the heater fighting with the fan.
>27 (degC) Turn Heater OFF
turn power to Fan ON
modulate fan speed via PWM
turn heater ON
turn fan OFF
Auto / Manual.... From the host I would like to be
able to set if the temperature control scheme is in auto or manual.
manual it means the host can toggle the corresponding outputs for heater ON/OFF,
Fan ON/OFF and fan speed via PWM value and the BAE0910 is just a dumb device
with PWM capabilities.
"Auto" the AE has control of the outputs as per the table above and ignores any
requests from the host to override the outputs. I have assume
"Auto/Manual" can be an internal variable within the BAE0910 that can be set
from the host or internal AE.
Failsafe....Again like above with a watchdog pulse however
in this case set a pre-determined setpoint and force the AE into Auto
Timed Deadband.. Although not for temperature control, if
the above was used for pH control it is simple on/off control to dose
pressurised Co2 into the Aquarium.
example. >6.40pH output
=ON <6.35pH output = OFF.
However the output cannot turn on again even if above setpoint
for xx minutes. Thus if the output is ON and the pH goes below 6.35
the output turns off, even if the pH goes above 6.4 again the output does not go
on again until an internal timer has elapsed.
1) Is the above feasible
2) Although I can use an RTD and transmitter to get 1-5VDC
representing a temperature signal, what I would really like to do is to direct
connect a single DS18B20 to the PIO pin and read temperature direct into the
AE. i.e. A single DS18B20 and only retrieve the temperature, no need for
ID and all that fancy stuff. RTD / Transmitter = $75.00 vers
2) Can the AE scale the ADC so we work in real engineering
units ? or do I work in 0-xxx counts. I would like to be able to send to
the BAE0910 a setpoint in degree's not counts and also read the value back
in engineering units.
I have 2 x DO and 1 x PWM output and 1 x ADC (or future DS18B20 using a PIO pin
more applications however the above two would get me
I'm pleased to announce the
BAE0910, a new multifunction 1-wire slave device!
Functions such pulse
width modulation and embedded logic are now possible on your 1-wire
The BAE0910 was the missing link of most 1-wire projects.
All theses features are
integrated in a single soic-8 package with direct connexion to DQ (require
- 1-wire compatible
- up to four PWM (pulse width modulation)
- one strong OUTPUT (sink/source up to 20mA)
- one PIO with integrated pull up/down
- one 32bit COUNTER input
- one 8bit ADC input with averaging & totalisation functions
- direct control of up to four R/C servo's
- 32bit RTC
- 1Kbyte eeprom
- 32byte user RAM
- AE AutomationEngine: embedded logic interpreter with four concurrent
- firmware upgradable via 1-wire
Complete documentation datasheet is available
Special thanks to Paul Alfille for integrating support of this
device in OWFS project and for the constant feedback he provided during
development of the device.
Starting on version 2.7p29, OWFS integrate
support for BAE0910.
The BAE0910 chip is already available for order
online and a tiny board (13x36mm) integrating the BAE0910 is also availlable
on preorder now.
Visit www.brain4home.eu for more info.
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