www.coridium.us/forum

I am wanting to help eval the LPC812 , so I got the sample, and am now going to use it as a
basic HVAC controller for my cabin & woodstove & ventilating fans.

I want to use the A/D comparator to set my temperature threshold. A 10K pot to do the
setpoint and an IC temp sensor for the other analog input. I will attempt to use the
register for a 'comp flag' as I don't have enough pins to use the 'comp_out' pin.

Brief scan of the C help file doesn't come up with any a/d comparator type of help info,
nor the forums [ in fact 'a/d' won't search - it reports back that 'a d' is not valid - needs
3 characters !!! ]

Bruce, have you started/completed any rough info ?? If not , I would try to provide some
basic info that should fit into the Help file and also perhaps a adcomp.c & .h file. I
don't want to duplicate what you may have already done. Any guidance/direction would
be accepted - I want to help and not be a NOOB PTA !!

feel free to put this in an appropriate place -
should I add to the post as I go along or put individual items in their own post? (in one of
the other forums?)

Thanx, gz aka olzeke51

The 812 does not have any A/D channels, it is a purely digital part.

True - it doesn't have a/d channels, however
there are two pins that feed an A?D comparator and one output pin (matrix enabled on all 3 pins)
Page 8 of my product data sheet lists that as being on pins 19, 12 and 18 for output.

There won't be any builtin support for the comparator in BASIC, but you can enable that function and access the comparator using register read/writes in BASIC. Details on how to do that in chapter 13 of the NXP User manual.

I haven't written any code for that function yet.

the latest MakeItC download (June 01 1600hours) doesn't include DS or UM pdfs for the LPC8xx series

Thanks for letting me know, I'll add those.

I just copy the latest versions from the NXP website and move them to the Coridium site (so that the link never breaks), but that means I may have a down rev version, until I notice or someone else does.

PROJECT ON HOLD, I need to get the well pump monitor(aka 'simple event monitor') done now - it is drought season here in So. Oregon.

Fired up the solder iron so I did some work on my '812
bought some AdaFruit arduino proto-shields, as I already had
the AdaFruit arduino-datalogger sheild. (having some trouble
with my I2C coding -- so I created the RTC_fake.bas program.
(it's in the Projects-simple event monitor).
1)I used a long-tail memory socket to mount the 812.
2)isolated the proto LED sockets - 2a)one at the end of the 'digital'
will be used for SCL/SDA connection [ the datalogger has these on
it - as well as my 'Leonardo' - but the pads on the datalogger also
had to be modified -cut the traces from the last two AD pins to the
SCA/SDA pads (evidently the earlier arduinos used the AD pins for I2c)
I added sockets so the two pins would mate with the datalogger SDA/SDC
SO - 812 SDA/SDC are wired to the two pins -- NOT the AD pins
2b)I needed a 'blinky'/test LED tied (via a 1k ohm) to +3v -- that is
the white looking jumper cable
3) the short buss across the end of the shield was wired to the +3v of
the 812 chip - CAUTION - the onboard zener is 150mwatt - ie 75ma max!!!
4) I wanted/needed an input so I wired a test jumper cable to the "S1"
switch - which goes to ground when you push it. the loose resistor will
most likely get wired to +3v for a pullup (via 1kohm)
so you have +3v ---1kohm---jumper-- N.O. switch./ .NC to ground
5)[/b]where would you be without a RESET !! - so the reset switch is
wired to the 812, but also the ICSP connector - so I could pick up the
RESET from the shield on top of the 812-(later I noticed there is a
RST pin on the voltage/ AD connector side of the shield)
you MIGHT want an RC setup on the this pin - small time delay when in
standalone mode (ie. no dongle)
6)on the edge of the serial connection(812) there were two small
thru-holes for +5, GND - which also got wired to the shield busses
FUTURE - add a 5v connector, possibly a VBAT/diode/5v regulator
7) the red LED off the end of the board is tell me that the +3v is
working - again 1kohm -- keeps the current draw low - I noticed that
the LED tends to 'brown out'/flicker sometimes so a smaller value might
be a good idea.
VOILA ! ! instant eval test bed (NOT!! - 3 TO 4 hours at least!)

Whats an eval chip in HVAC controller?

Coridium offered (still is, I believe) an LPC812 chip to evaluate.see the home page
So, I needed a project to test it out - so I created my own HVAC controller project.
Basically it would monitor temp via I2C, display it on an LCD, and turn on/off some
fans for ventilation/circulation [Heating Ventilation And Circulation!!]
I have a woodstove for heat-BTW.
Regards, olzeke51
PS. it is backburnered -- the AD comparator conflicts with the serial data and reset pin