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treitmey
Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA
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Tri state input/output chip |
Posted: Fri Jun 24, 2005 1:26 pm |
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I am looking for a chip I can put on port d. I would like it to be in transparent mode or tri-state mode. The problem is I want different pins on port be to input and output,... set_tris_d(0b10011010).
Which chip can do both input and output in transparent mode. then switch to tri-stated. I was thinking 74HC573. Can this work in both input and output at the same time?
Last edited by treitmey on Fri Jun 24, 2005 2:39 pm; edited 1 time in total |
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Steve H. Guest
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Posted: Fri Jun 24, 2005 2:02 pm |
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Tri state is really just input mode where you don't read the input, right? For port expansion I have used the Maxim MAX7301, it is an SPI device with pretty good drive levels. Fully programmable for bi-directional I/O.
Philips also makes a I2C device, but as I recall it only has week pullup on output not a true push/pull drive.
Regards,
Steve Hageman |
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treitmey
Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA
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Posted: Fri Jun 24, 2005 2:10 pm |
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No. When I say tristate, I want say 8 of these on the port D and then use a 3-8 de-mux to pick the device. so 1 device is active and the rest are tristated.
Good idea the max7301, but I think that may be too slow.
I'll get a sample and experiment.
I think the closest is the 74HC245 transciever.
BUT that is all in or all out. NOT A MIX
Last edited by treitmey on Fri Jun 24, 2005 2:17 pm; edited 1 time in total |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Fri Jun 24, 2005 2:15 pm |
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Quote: | I wanted the interface to (for example) a 12 key keypad | Why do you need an external chip to do this ? Why can't PortD do it ? |
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treitmey
Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA
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Posted: Fri Jun 24, 2005 2:19 pm |
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I would like fast IO to say, my keypad, my lcd, my relays, my dip addresses, my wiegand reader(4 readers) ... I run out of pins fast,.. so perhaps the solution is a bigger uP. |
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Mark
Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA
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Posted: Fri Jun 24, 2005 4:41 pm |
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Bigger pic or have you thought about using another pic to do what you want. |
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treitmey
Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA
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Posted: Sat Jun 25, 2005 5:44 pm |
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yes, I thought about that, not the cleanest, tho...
I'll use this as an excuse to get a bigger chip and lean something new.
(really thought the 18F452 would hold me for a while) |
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diogoc
Joined: 12 Feb 2008 Posts: 19
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max7301 |
Posted: Sat Feb 21, 2009 8:13 pm |
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I want use max7301 with spi interface. someone have some code example?
thanks |
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