Re: [AVR-Chat] 5V - 3V interfacing
2007-01-22 by dlc@frii.com
I have used the resistor method with XBee 3.3v units with no problems. Remember that you only need them on your outputs to the device. Don't make the values too high or you could make the waveform distort at high data rates. DLC Dennis Clark dlc@frii.com via Palm TX
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-----Original Message----- From: "kernels_nz" <hein@mediflex.co.nz> Subj: [AVR-Chat] 5V - 3V interfacing Date: Sun Jan 21, 2007 3:58 pm Size: 1K To: AVR-Chat@yahoogroups.com Hey guys, Anybody know what the best way is to interface a 5V output on my Mega64 to a 3V input on a Nordic RF IC ? The Nordic datasheet specifies a max input voltage of VDD + 0.3V (3.3V) Best way I could come up with was a voltage divider on each line, but theres six lines, so thats 12 extra resistors ! I need to run the Mega at 5V because of interfacing to other 5V components, so running it @ 3V is not an option unfortunately. I assume that outputs from the Nordic IC to input pins on the Mega will be no problem for straight connection due to the high input impedance of the Mega and I would not need to use the pullsups on the Mega because the RF IC drives the line both low and high. It looks like anything above 1V on the Mega is seen as a 1. Any insights would be appreciated. Thanks Hein B Auckland, New Zealand. Yahoo! Groups Links