Hello, I Use 2 sparkfun DAC's (MCP4725). and drive the with testDACSpec.ino (1.5 KB)
I have 2 of them on the Mega. I did not cut the pull up resistors on one of them since it seems to give problems only when using 3 or more.
My problem is that the voltage on the output is not what I would expect. I expect a voltage related to the given value in the table.
Theese are the measured voltages:
address(hex)=61 lookup=0 lookupWa=200 an.value=496 voltage=2.54
address(hex)=61 lookup=1 lookupWa=400 an.value=509 voltage=2.43
address(hex)=61 lookup=2 lookupWa=800 an.value=494 voltage=2.51
address(hex)=61 lookup=3 lookupWa=1000 an.value=506 voltage=2.43
address(hex)=61 lookup=4 lookupWa=2000 an.value=508 voltage=2.48
address(hex)=61 lookup=5 lookupWa=3000 an.value=753 voltage=3.67
address(hex)=61 lookup=6 lookupWa=4000 an.value=880 voltage=4.28
address(hex)=61 lookup=7 lookupWa=4095 an.value=876 voltage=3.97
I also need 0.5V and 4.5 V and cannot produce them. The output has no load at the moment. My arduino powers on the USB.I provide 5V for the DAC's coming from the "5V" on the mega.
Thanks for suggestions.