I build a little dmx dimmer for ledstrips.
I burned the sketch in my processor before I mounted it on the pcb with an uno running ISP.
All works well except: I'm not able to upload my sketch once the processor is mounted.
Not with the serial port nor with an uno running ISP.
Can anybody see what's wrong in my schematic?
Your MAX485 is connected to the the TX/RX of the processor; that might interfere with upload over serial. The other problem can be that you did not burn the bootloader (or erased it) while uploading using the UNO.
Not sure why you can't upload using the SPI pins.
I would expect problems with your 7805 regulator. You need high frequency bypass on both the inputs and outputs. Check this data sheet: file:///home/gil/Documents/DataSheet/LM7805.PDF page 21. How do you connect the programmer, I do not see a defined port for that.
In addition to what @sterretje mentioned, I would be suspicious of the DC/DC converter. Try to upload with 5V external power (like a wall wart or good power supply).
Thanks for all your help so far!
Never came to mind that burning with a programmer would not install the bootloader.
A broken jumper wire was the problem of programming with SPI pins. (oops)
So I was able to burn the bootloader to the processor.
Unfortunately this didn't fix the programming with the serial port.
On previous projects I was able to program this way with the max485 connected.
As long as there is no dmx signal.
But I'll try to desolder the max485 later this week.
Could it be the powersupply?
This is the dc/dc converter I used.
The pcb is powered with the 24v led powersupply.
Is this ok or should I change something here?
https://nl.farnell.com/recom-power/r-78e5-0-0-5/dc-dc-converter-5v-0-5a/dp/2078564
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