I have been working on our next detection system quite long. Overall have great experience with Arduino for about three years almost without any bigger problems.
Now I am modernising some very old precise measurement equipment.
Basic scheme of operation - reading analog sensor with voltage divider and doing some mathematical stuff with it (and printing to serial port, lcd display, and SD card).
But, even my project is almost finished (from software point of view), I have faced following huge problem:This is NOT a software issue, when powering from USB everything works fine !!!
When arduino is connected to +12V power supply (I have tested 3 different), all serial SPI devices doesnt work as they should. Arduino onboard regulator seems to heat a lot, but there is very low ambient temperature (about 10 Celsius degrees) so it shouldnt affect this.
The colour SPI LCD (ST7735) displays a random data when it has to display bitmap from SD:
Otherwise when I write black to full screen it works fine:
Also rewriting small areas with lines and text works fine:
And the main problem - when trying to read/write data to SD card causes havoc on card (BTW file RSSlog.TXT created by Arduino is empty):
Here is a image how the components are wired (for illustration only, sorry fro mess around):
Any ideas what could cause this?
I am thinking about some kind of interference or jamming from pulse converters (detector needs negative 12V and negative 300V). I also added a ferrite core filter on data wires, but it seems not having some remarkable effect....
Thanks in advance !