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<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009>Zdravim,</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>mam jednoduche
zapojeni s I2C prevodnikem PCF8574, ktery na vystupu</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>spina (ma spinat)
12V relatka pres ULN2803A. Pri napajeni 3.3V toho PCFka</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>nemam dostatecne
napeti na sepnuti toho ULNka. </SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>Pri tom v datasheetu
je u toho ULN uvadena hodnota pro sepnuti 2V, </SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>to PCFko by melo mit
HI-uroven 0.7*VDD = 2.3V. Tolik teorie.</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>Ve skutecnosti mam
na vystupu toho PCF jen 1 az 1.5V, coz nestaci</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>k
sepnuti...</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>Kdyz jsem to zkousel
samsotatne, tak naprazdno je vystup z PCF pres</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>3V, takze tady
problem nevidim. Kdyz ale pripojim to ULN, napeti klesne</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>na zminenou hodnotu
cca 1V. Vstupni proud by mel byt u toho ULN</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>nejakych 1.5mA,
takze to by snad nemelo to napeti tak srazit....</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>Napetove pomery jsem
pri zkouseni "na prkenku" pri napajeni 5V </SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>nemeril, ale
predpokladal jsem, ze pri tech katalogovych hodnotach </SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>to bude pracovat i
na 3.3V....</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009></SPAN></FONT><FONT
size=2 face=Arial><SPAN class=144232315-02112009></SPAN></FONT><FONT size=2
face=Arial><SPAN class=144232315-02112009>Kde delam chybu ?
</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV><FONT size=2 face=Arial><SPAN class=144232315-02112009>Dekuji za
odpooved</SPAN></FONT></DIV>
<DIV><FONT size=2 face=Arial><SPAN
class=144232315-02112009></SPAN></FONT> </DIV>
<DIV> </DIV>
<DIV align=left><FONT size=1 face="Courier New">--<BR>--
-------------------------------------------------------------------<BR>Martin
Patka
network & server
administrator<BR>----------------------------------------------------------------------<BR>Mikroservis
v.o.s.
e-mail: </FONT><A
href="mailto:martin@mikroservis.cz"><FONT size=1
face="Courier New">martin@mikroservis.cz</FONT></A><BR><FONT size=1
face="Courier New">Nerudova
45
phone work: 481 624301<BR>51301, Semily
1
phone VoIP 481 120969<BR></FONT><A href="http://www.mikroservis.cz/"><FONT
size=1 face="Courier New">http://www.mikroservis.cz</FONT></A><BR><FONT size=1
face="Courier New">--
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