andy pugh wrote: > On 14 April 2012 22:45, Kirk Wallace <kwall...@wallacecompany.com> wrote: > > >> A 660 Ohm >> resistor pulled the ramp up higher, but 5V / 660 Ohms = 7.5 mA and is >> starting to get into an amp range that could get interesting for pin 16. >> > > I thought that nearly all p-ports can _sink_ 15mA per pin? > http://www.asix.com.tw/FrootAttach/datasheet/MCS9815_Datasheet_v200.pdf > has the "drive strength" at 12mA for the p-port pins, but does not > specify source or sink. > I use 390 Ohm resistors pulled to +3.3 V on my interface boards. And, they can be daisy-chained, so that is 195 Ohms to +3.3 V when you use two. So, when driven low, it is almost 17 mA with two boards, and 8.5 mA with one board.
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