Hello
I did not understand very well what has to be done to tiny to get the analog input to work.
I have the newest firmware installed!
Where do i have to change the offset?
Thank You for help!
Have you read the section Connecting An Analog Signal in http://www.vems.co.uk/VEMSWB/UserGuide/README.html?
There are no offsets deal with, although you will have to do a little bit of customisation work to scale the value that you're trying to log and the resistor that you're using.
What are you looking to use the Analog input for?
Rob
hello, im the originator of this question
I have read that topic and also the topic where i originally posted this
i have hooked up the vems map sensor to analog input and i get 0 voltage reading
i tested the map and i get a reading from it directly!
In previous topic people stated that there is a problem with firmware configuration? and offset has to be changed for analog input to work?
Thank You!
You'll need the most upto date firmware http://www.vems.hu/download/round/round_2007-04-25.zip which you'll need to unzip and upload to the gauge.
In the directory \round_2007-04-25\MegaTune2.25\mtCfg you'll find a file round.ini
Scroll down to the section [OutputChannels]
and at under the line internaltemp= scalar, U08, 13, "", 1.000, 0.000
add the line analogIn = scalar, U16, 22, "kPa", 1.000, 0.000
Then below o2 = { o216bit / 2560}
add the line map = { (5/255)*analogIn } you will have to play with the equation to get it to reflect the value you're wanting.
To include the value in the datalog go down to [Datalog]
and change the line entry = boost_pwmpct, "boostPWM", float, "%.2f"
to entry = map, "MAP", float, "%.3f"
Before connecting my analog input wire to TPS i measured it and i get 4V from it? is that ok? it should be input not output...
It is correct, there is a reference voltage applied to the input line, the strength of the TPS signal should pull it down to the correct voltage - you may want to use a resistor in line to make sure that the voltage does not effect the TPS reading in some cases.
Quote from: [email protected] on April 29, 2008, 09:20:13 PM
It is correct, there is a reference voltage applied to the input line, the strength of the TPS signal should pull it down to the correct voltage - you may want to use a resistor in line to make sure that the voltage does not effect the TPS reading in some cases.
OK, then i'll try with resistor, becase without it the TPS reading is effected.
You can use quite a large resistor as the A2D is a high precision unit so reducing the voltage wont kill the tps accuracy much.
If you feel comfortable with firmware upgrades you might want to try:
http://www.vems.hu/download/round/round_2008-02-12.zip
As it has some analog in and out improvements.
Rob
Hello!
Is it possible to disable the reference voltage 4V from the input? I want to put map sensor signal with 10 k resistor to the gauge, but the signal is weak and cannot pull and push away enough from 4V.
The internal pull-up cannot be disabled.
And desolder it? Is it work w/o the pullup? Does the vemsgauge have public schematic? How can I calibrate the input if I want to put this map on it: http://cosworth.hu/content/hasznos/Weber-Marelli%20sensors/aps02_03-05_01.pdf
Thanks
Which pull-up resistor are we talking about? There is an internal pull-up to dampen noise, and we recommend a resistor:
http://www.vems.co.uk/VEMSWB/UserGuide/README_files/WBAnalogIn.png
But this is so that the voltage on the pin (brought high by the pull-up) does not effect the sensor you are reading from.
Usually you will find that there is enough resolution to read even the smallest signals.
There is no public schematic and the units are not serviceable
Okay, I put the map signal across this resistor (somwhere in wiki I read 10k for it). The sensor signal on atmospheric pressure is about 2.5 V. With linear input curve (new firmware, 0-15-30-45 and so on), with calibration 255, with offset 0, megatune show about 1418. If use some vacuum (map signal is about 1.8V), megatune drop to about 1350 (if I remember good), so the input changing not to much. I would like calibrate it to show something like pressure or any readable format.
I will try do a log, maybe understandable....:)
If these figures are correct it means:
A change of 700mV gives a change in reading of 68, which is pretty close to being an accuracy of 10mV a unit.
The range of the sensor is 250mV to 4750mV = 4500mV / 10mV = 450units.
The APS05 is shown to read from 17kpa to 308kpa = 291kpa / 450units = 0.64kpa
So you will have around 0.65kpa resolution.
You do not have to use that resistor, it was put in line when we were taking a reading from a Mass Air Flow sensor, and the pull-up on the analog in pin was causing the MAF output to rise.
Putting the sensor's Signal Out directly into the analog input would be a useful experiment.
Thanks!
Yes, I see the resolution is enough, I will try find some equation for human readable output.
I will try w/o the serial resistor.
I have another question, but about the rpm input, so I will ask there:)
Cool - let us know what the raw value is when you remove the resistor, we should be able to work out the equation from there.
I have made the measurement. The result is half good half bad.
The range of the sensor is 250 mV to 4750 mV from 17 kPa to 216 kPa, with linear out.
On athmospheric pressure it shows 2400 mV.
I got this without serial resistor (the map sensor signal into the vemsgauge analog input):
(http://www.vems.hu/files/MembersPage/ZoltanAlmasi/map_table.gif)(http://www.vems.hu/files/MembersPage/ZoltanAlmasi/map_graph.gif)
The positive range is nearly linear, but the vacuum is unusable. The sensor can't pull the signal below 2400 mV, so unable to measure below athmospheric pressure. (without connected signal line the map sensor out is working properly of course).
I made another measurement without the sensor:
disconnected analog in (4v) megatune shows 1520
pull the ground (0V) shows 1040
pull up to 5V shows 1600
There is a breakpoint at 4V. Unfortunatelly I didn't have a variable resistor at hand to do more measuring point.
I think the reference voltage on the gauge input makes problem to use the analog input correctly.
Thanks for that, I've not seen anything quite as concise and well researched for a while.
You will really need to post this information on the Wiki, I would suggest on this page:
http://www.vems.hu/wiki/index.php?page=AfreshTiny/AnalogInput
Posting what you have here may result in a positive response.
Ok! Thanks your very fast reply. I put the info on the wiki.
I have made real logging last saturday with a bmw v8 kompressor. The analog input calibrated to show absolute pressure with this curve:
analog input curve 11 (165) 97
analog input curve 12 (180) 158
analog input curve 13 (195) 170
analog input curve 14 (210) 206
analog input calibration 32
analog input offset 0
This is the log file
http://www.vems.hu/files/MembersPage/ZoltanAlmasi/datalog200811151111forgatas.xls (http://www.vems.hu/files/MembersPage/ZoltanAlmasi/datalog200811151111forgatas.xls)
The result is seems good. Only the rpm input has similar problem as Ranz here:
http://www.vems.co.uk/forum/index.php?topic=464.0 (http://www.vems.co.uk/forum/index.php?topic=464.0)
hi, i still cant calibrate my 300 kpa sensor..
(http://shop.vems.hu/catalog/product_info.php?cPath=1_12&products_id=89)
is there a graph/chart for that sensor, too?
on athmospheric pressure, my DVM shows 2172 mv, but that doesn't fit in the chart, ive made up on the ranges (0,2v-4,8 and 20-300kpa)
Theres a datasheet for the sensor here:
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-34/DSA-677433.pdf
And theres a graph on page 3 giving the voltage out.
that sheet data is similar to the chart i've made up..
but why do i measure 2,171 V when no pressure is connected to the MAP sensor (my city is 55-100m above sea level)
that should mean, there is a pressure of apprx. 140 pka?! i don't think so :(
Can you check that your feed to the sensor is actually 5v?
well the sensor has a 12v input and a 5v output..
and the input is connected to my car battery..
or what do you mean?
Is this voltage being read with the MAP sensor connected to the Wideband gauge?
yes..
There is a pull-up on the gauge's input, if you disconnect it briefly you should see the same voltage as in the data sheet.
Then you'll be able to work out the voltage offset to add to that graph.
This pullup is make troubles for everybody :)
My original audi bosch 200BAR MAP voltage did not change, was round connected or disconnected, no change on voltage. When voltage is affected you should use resistor (10kOhm?) because otherwise ecu is going to get wrong boost reading.
Did some testing on my own. VEMS 300BAR MAP sensor shows at absolute pressure 1,654V, when I connect round to it, it shows 2,1xx. Now i soldered 10kOhm resistor to wire but still the reading is affected, 1,8xxV, tried with 40kOhm resistor... then it's almost stable, 1,681.
Now i'll try to get the reading right @ the gauge, more testing testing testing :P
EDIT: with 40kOhm resistor it's not possible to calibrate, the signal is too weak. But doesn't diode do the trick? I'll try that tomorrow.
EDIT1: No, the diode does not work, reference voltage is higher than MAP output, with diode it will show only values higher than 4V.
Now i visited one friend and he said that it's no problem to do little schematic and it should work... I'll keep you informed.
EDIT2: it works :) the schematic is very very simple, I'll post it later (friday i think).
(http://ranz.planet.ee/analoginskeem.jpg)
With this schematic the MAP output is not affected and you can connect signal from OUTPUT directly to the gauge.
For VEMS 300BAR MAP my analog in gauge settings are:
Firmware version: 2009-03-03
Calibration: 64
Offset: 0
Analog in curve:
0
0
0
0
0
0
0
0
0
3
38
73
107
136
169
225
240
Now gauge shows pressure in kPa.
Button thereshold is 128 and button changes value when you hold it 1 second. If you just press it once, it does nothing, when you hold too long, it shows something like -FA, press again and it goes back.
Awesome work there, thanks for posting it.
It should work also without capacitor, but we used it anyway.
Hello,
has anyone tryied analog in to show (water) temp? How to connect the (wems webshop) ntc sensor to gauge? one wire to analog in (pin8) series with a resistor (size)k? and the second wire to? ???
Tryied with connecting the second wire to ground. Changed the button threshold and then got it to work with 15k resistor, but the analog value isn't stable and the curve is narrow..