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Project Guidance / can to k-bus communication
Last post by undeadcycle - Today at 12:33 am
Ok, so this is my first arduino project. The goal is to remove the speedometer from my 2001 BMW 330i. The speedo is the unit that connects the two in car networks: the canbus and the k-bus. I have an arduino uno clone (redboard), a canbus shield, and a resler USB k-bus interface. I also have a raspberry pi I plan to use to run a digital speedometer if it is required. I have played around with the arduino a little and I can read canbus messages. I just got the resler interface and have not had the chance to play yet. I have been looking around for some code that will write from the usb to the can shield and vice versa but have been unable to find it. If anyone can point me in the right direction I would greatly appreciate it. Thank you.
Project Guidance / Re: Arduono hid text display o...
Last post by pert - Today at 12:33 am
The quick answer is "no" since the primary microcontroller on the Uno and Mega (ATmega328P and ATmega2560 respectively) don't have native USB like the ATmega32U4 on your Leonardo.

The more complex answer is that if you have a genuine Uno or Mega, or a clone with the same USB-serial chip, there is another microcontroller normally used only for handling USB communication between your computer and the primary microcontroller. That chip is the ATmega16U2, which does have native USB support. It's possible to hack that chip to do what you want but it's a very advanced process. You can find more information here:
LEDs and Multiplexing / Re: if statement problem
Last post by Wawa - Today at 12:33 am
They are great ! !
Cover your hot coffee with one, and leave it on there for ~20sec.
Then flip it, and leave for another 10sec.
Warme stroopwafels.
Hi Luck,

You're doing that all wrong.

Delete all the "printDebugMessage" lines you've added. Than go and look at the top of IbusGlobals.h, and make sure "#define IBUS_DEBUG" is not commented out. While you're there, make sure "#define MELEXIS" is also active (not commented). As long as you have everything connected correctly, you should see plenty of debug text in the serial monitor.

It would make life much easier if you just posted all your code (attach all files, including the library files), and I can see if everything looks good.

If you can also show how you have the Melexis TH3122 connected to the Arduino, it would also help. If you're not working in the car, do you have the iBus line pulled up to 12v through a 1K resistor ? You won't see anything at all unless the iBus line is pulled high.


Displays / Re: Mcufriends – distorted pic...
Last post by david_prentice - Today at 12:28 am
Your "Screeen OK"
1.  has similar ADC resistance values :  28, 29.   25, 30 is normal
2.  Calibration values look normal

Your "Diane NOK"
1.  has very unusual ADC resistance values :  31, 48.   25, 30 is normal
2.  Point cy values look inconsistent.
3.  Calibration results are very unusual for LEFT, RT

Your "Victoire NOK"
1.  has normal ADC resistance values :  24, 34.   25, 30 is normal
2.  Calibration values look normal
3.  YP, XM pins are different to all the others

Your "Manny NOK"
1.  has slightly unusual ADC resistance values :  28, 30.   25, 30 is normal
2.  Point cy values look crazy.
3.  Calibration results are very unusual for LEFT, RT

Did you buy all four screens at the same time?
Did you buy them from the same Vendor?

Although Ebay has described the 2.4 inch screens as SPFD5408,   no geneuine 0x5408 IDs were detected until recently.

Obviously a batch of SPFD5408 screens have just come onto the Ebay market.

Someone else reported "similar" resistance values for X, Y on her 0x5408 screen.
All the other rectangular screens give different resistance values i.e. ~25, ~30.

I suggest that you just buy four new screens and put it down to bad luck.
You can always use the duff Touch Screens for non-Touch projects.

Programming Questions / Re: Missing SoftwareSerial, ev...
Last post by pert - Today at 12:27 am
where I should begin?
I would start by writing a minimal "hello world" sketch that just sends some data over Bluetooth. Save that sketch to use for testing purposes later if you need to do troubleshooting. It's always nice to have a quick sanity check when things are going wrong with the complex project to ensure that, yes, the Bluetooth module is still working.
Microcontrollers / Re: Attiny 44 in boot loop
Last post by Tero - Today at 12:25 am
I did 'burn bootloader'. I also tried disabling watchdog. Neither had any influence on the problem.

I'm starting to wonder if It's possible that my MCU is damaged. I soldered it with proper grounding, so it is hard to believe.
General Electronics / Re: Which relay to use for my ...
Last post by SAMVAR - Today at 12:25 am
Thanks a lot for that Mike,

So is my current 10A relay switch suitable for 2kw appliances?


Also, the fact that the relay has a 5v separate power supply is throwing me. Is this also up to the task?
How many samples in 30 seconds?
Microcontrollers / Re: PB: Standalone Atmega328 f...
Last post by pert - Today at 12:24 am

The pull-up resistor is not absolutely necessary because there is an internal pull-up on the reset pin but it isn't a very strong pull-up so if you have a lot of electrical noise it could cause mysterious random resets of your microcontroller. For that reason it's safest to just throw a resistor on the pin since it could save you some big headaches later trying to figure out what's going wrong.

You can sometimes get away without the decoupling capacitors but it could lead to unreliability so again it's safest to always use them.
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