Anyone know whether its possible to drive 2 LCD displays at once .
I need 4 X 16, and its much cheaper to buy 2 2 X 16 displays, than 1 4X16 display.
The pic needs to see the display as the one display so that locate commands can
handle the 4 lines.
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Yes, works fine, but you'll need seperate pins for each LCD's Enable signal. Get one LCD working first, in either 4-bit or 8-bit mode. Then add the second LCD, data lines will overlap with the first LCD. In your code, you'll have to pull Enable low for the LCD you want to talk to.
I was playing with the idea of seeing how far this could go… but there's probably some capacitance problem with too many LCD's using the same data lines.
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Hi mauried,
Some time ago , I tried to connect several LCD displays , and I used 74LS573 Octal D-Type Latch with 3-STATE Outputs .
I think you take a risk to destroy your LCDs displays if they are connected in parallel .
Have a look at 74LS573's functions tables , they are very easy to use .
To command either display 1 either display 2 , you have to specify what display you want to use in your code .
DO to D7 of two 74LS573 may be connected in parallel . Their 3 states O0 to 07 latch-outputs are connected to each LCD display
They must be controled in 4 bits mode .
ie: O0 may be connected to RS , O1 to RW and O2 to Enable , O4 to O7 to D4 to D7 of LCD display
D0 to D7 may be connected to PortB.0 to PortB.7 of Pic Microchip (or another Port of your choice) .
You have to use Two others ports to enable (Latch enable pin ) either one 74LS573 or one another . Their "Output enable" pin is connected to 0V .
So , when hou'll use one display , the other 'll continually display the previous message
Regards
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Anyone know whether its possible to drive 2 LCD displays at once .
I need 4 X 16, and its much cheaper to buy 2 2 X 16 displays, than 1 4X16 display.
The pic needs to see the display as the one display so that locate commands can
handle the 4 lines.
Yes, works fine, but you'll need seperate pins for each LCD's Enable signal. Get one LCD working first, in either 4-bit or 8-bit mode. Then add the second LCD, data lines will overlap with the first LCD. In your code, you'll have to pull Enable low for the LCD you want to talk to.
I was playing with the idea of seeing how far this could go… but there's probably some capacitance problem with too many LCD's using the same data lines.
Hi mauried,
Some time ago , I tried to connect several LCD displays , and I used 74LS573 Octal D-Type Latch with 3-STATE Outputs .
I think you take a risk to destroy your LCDs displays if they are connected in parallel .
Have a look at 74LS573's functions tables , they are very easy to use .
To command either display 1 either display 2 , you have to specify what display you want to use in your code .
DO to D7 of two 74LS573 may be connected in parallel . Their 3 states O0 to 07 latch-outputs are connected to each LCD display
They must be controled in 4 bits mode .
ie: O0 may be connected to RS , O1 to RW and O2 to Enable , O4 to O7 to D4 to D7 of LCD display
D0 to D7 may be connected to PortB.0 to PortB.7 of Pic Microchip (or another Port of your choice) .
You have to use Two others ports to enable (Latch enable pin ) either one 74LS573 or one another . Their "Output enable" pin is connected to 0V .
So , when hou'll use one display , the other 'll continually display the previous message
Regards
Of course ,you have to use One 74LS573 for each display . So , with that configuration ,you can control as many LCD Displays as you like