Hi, I'm new.

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Andrew Cowan

Senior Member
Coolant temp - use a DS18B20.

Voltage - use a voltage divider.

Screen - do you have a particular oLED screen in mind? Once we know that, we can choose a PICAXE. I'd go with the 20X2 or 18X, if it is a parallel driven screen. maybe the 14M if it is a serial screen.

Welcome to the forum!

Andrew
 
G

gamble

New Member
Thanks for the help. I don't have a screen in mind, something kind of basic and easy to use. With the coolant temp and voltage can I just tap into the existing wires in the car instead of adding a new sensor?
 
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MPep

Senior Member
Regarding the voltage, you will need to make sure that the 'sensed' voltage range is within 0-5V. So you will need a voltage divider, 2 resistors.
If you apply 12V directly onto one of the PICAXE pins you will let out all the 'smoke' that is stored inside!!:eek:

For the temperature, use (as suggested by Andrew) a DS18B20. In the manual, read up on READTEMP.
 
A

Andrew Cowan

Senior Member
Would the axe033 suit your needs as a screen?

It is very easy to use, cheap, and it will display two lines of text (16 characters per line.)

a
 
W

westaust55

Moderator
OLED displays

While I am currently adding the 4D systems range of modules to PEBBLE, I have taken the opportunity to do some reading about their oLED displays.

Others on this forum have also used the 4D Systems OLED modules.
An potential advantage over the LCD type display is that they are illuminating without the need for a back light and have a wide viewing angle. Thus IMHO making them more suited to vehicular applications where good visibility in a brief glance is required.

While the AXE033 is great for many purposes, the basic LCD supplied with the AXE033 LCD module does not include a backlight.

The 4D Systems OLED displays are available in serial comms versions, they are auto baud rate detecting and available in 96, 128 and 160 pixel wide screens.
Have a look at www.4dsystems.com.au. They list sellers worldwide on the Aust website.
 
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MurrayJ

Senior Member
Did you see that yesterday (29th Sept) they released their larger oLED displays, 2.4in, 2.8in and 3.2in LCD all 320 x 240 res including some with touch screens to the serial format?
 
G

gamble

New Member
MPep said:
Regarding the voltage, you will need to make sure that the 'sensed' voltage range is within 0-5V. So you will need a voltage divider, 2 resistors.
If you apply 12V directly onto one of the PICAXE pins you will let out all the 'smoke' that is stored inside!!:eek:

For the temperature, use (as suggested by Andrew) a DS18B20. In the manual, read up on READTEMP.
Click to expand...
I have to research my car and find out if my coolant temp sensor is a 0-5v which I'm sure it is. The volt meter would just be a simple power/ground I'm assuming?
Sorry for all the dumb questions, I have done lots of wiring on cars for carputers, amps, speakers, remote starts, alarms, gauges, accessories blah blah blah but throwing a circuit board in the mix gets me all confused.

Do you have a link/pic or actual pic of this? It may work out, depending on how big the text can be. I don't want to squint while driving.

I think I want to try this out on my daily driver first before it goes into my toy car. :)
 
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manuka

Senior Member
I don't want to squint while driving
Click to expand...
Quite understandable! LCDs certainly can be a pain to read in certain conditions, & their automotive use may be life threatening unless well thought out. In fact modern vehicle LCD instrumentation often fails in this respect. The speedo is usually great, but associated LCD trip/odometers can be almost impossible to read at a glance, especially during the day when reflections also arise. I won't shame makers by mentioning vehicles, but IMHO one of the worst starts with "T" - who seemingly forgot that the steering wheel further obscures the trip meter.

I personally find this most irksome when using the handy location system employed in rural NZ (789 Main Road = 7.89 km along etc). Driver distraction arising from buried trip meter checks may lead to hazardous narrow road "U" turns, or even livestock/tractors/vegetation/fences joining the journey as well!

For simple displays perhaps consider a 7 segment LED instead? These are bright,cheap & far easier to drive than LCDs- a 20M will handle one directly. => http://www.youtube.com/watch?v=Fw0lHWN1pj0 should give you some inspiration! Stan.
 
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M

Mycroft2152

Senior Member
Unfortunately 7 segment LEDs are very power hungry. At 20 milliamps per segment, you are pulling between 40 and140 milliamps. Battery life is relaively short.

Myc
 
D

Dippy

Moderator
My car's LCD dash display is perfectly clear and the separate smaller 'reverse' LCD display for other functions is perfectly clear.
My sat nav LCD display is lovely.

As to whether you need to squint you should simulate your text size and try it on your dash. 8 to 10mm text (with a nice resolution and font) should be perfectly clear if your eyesight is good enough for you to drive.

As to power consumption of displays it depends. If it's only working when the ignition is on or engine running then a few 100 mA isn't important.
Of course, you can PWM LED displays.
My car dash backlighting is PWMed.
(And drives me up the wall as much as LED rear lighting on modern cars... I wish they made it run faster but no doubt someone wrote some big cheques to get their own way).
 
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