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Ttelmah
Joined: 11 Mar 2010 Posts: 19221
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Posted: Sun May 21, 2017 8:16 am |
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Makes total sense. |
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temtronic
Joined: 01 Jul 2010 Posts: 9106 Location: Greensville,Ontario
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Posted: Sun May 21, 2017 12:50 pm |
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Gee Mr.T. I just don't underdstand it at all, the 'big picture' that is.
Using an I2C port expander doesn't make 'sense'. While you save 4 I/O pins, you've added a 16 pin device onto the PCB, so the PCB has to be bigger and more complex. Hmm... I'd just use a bigger PIC...
Also the LCD driver just got a tad more complicated, so more R&D time cutting/compiling/testing code
There's also the real additonal cost for the I2C device and PCB. Maybe not much, but it does add up.
It'll be interesting to see where this thread weaves next though !
Jay |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Sun May 21, 2017 1:10 pm |
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It may make sense if the LCD is remotely located from the main board
and you want to keep the cable size to a minimum. With i2c, it would
require only four wires: SCL, SDA, Vcc, Gnd.
Otherwise, it's 8 wires minimum. |
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temtronic
Joined: 01 Jul 2010 Posts: 9106 Location: Greensville,Ontario
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Posted: Sun May 21, 2017 1:26 pm |
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hmm... I can do it with just 2 wires, gnd and data....think of '1-wire' interface or the old MC14669 addressable UART of 3 decades ago...
bet not many heard or used that UART though.....
Jay |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19221
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Posted: Sun May 21, 2017 2:13 pm |
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What 'made sense' was PCM_programmer's comment about why the compile problem...
In fact there are I2C LCD's, or serial LCD's, so if it is just a matter of saving pins, much easier solutions.
The key though is that this is really about learning how to write code and compile it. |
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