With an atmel microcontroller when you write 1 to a pin does the pin actually read +5, or is that only when you have an internal pullup on that pin? Thanks Colin
- posted
18 years ago
Quick Microcontroller question
Loading thread data ...
- Vote on answer
- posted
18 years ago
Colin wrote this in :
It reads +5 when high. But be aware that most atmels can sink more current than they can source.
-- MVH, Vidar www.bitsex.net
- Vote on answer
- posted
18 years ago
It will be a "logic 1" but the guaranteed minimum voltage is 4.2 V. Check the datasheets; there is some variation among the AVR family in this parameter. Even with pull-ups, the actual value may be less than
5.00 V if you're sourcing current.-- Rich Webb Norfolk, VA
- Vote on answer
- posted
18 years ago
On the 8051 equivalents (89C52, etc.) one port is open collector, so requires an external pull-up, if I recall correctly.
Read The Fascinating Manual for the particular microcontroller you are using to be sure....
-- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca