AVR-Chat

I am having trouble understanding how a character is sent to the lcd 
display by way of at-keybd. I am using stk500 with 8515 mcu and 4x20 
lcd. I am using portd-pd2(int0) for clock and pd5(oc1a) for data. My 
question is,do I need a pysical connection from 8515 to lcd in order 
to pass data to lcd or is this passed by way of software code. My lcd 
is wired using porta and is currently working. I just want to grasp
an 
understand of the flow of data from keybd to lcd. Is the uarts 
transmit data out pin pd1 used(hardwired) or is it just coded via 
software to send data stored in registers and transmitted out to lcd. 
Is this what is meant by (softuart) or am I missing something here. 
Any help would be appreciated.

At 08:00 PM 17/07/2005, you wrote:
>I just want to grasp an understand of the flow of data from keybd to lcd.

The Keypad, LCD or UART have no knowledge of each other.
The software you write does know how to communicate with
all of them. A keypad is scanned by some ports, you then
need to translate this to ASCII code if you want to send
it to the LCD, the same thing happens with the UART,
you receive the data which may already be in ASCII format
and then you send it to your display...or you may want
to send what you scanned from the keypad to your serial
port....or both...as you can see it's up to you to decide
what you want to do.





Regards

John Samperi

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On Sun, 17 Jul 2005 10:00:20 -0000
 "Lupe" <lpnoah@hotmail.com> wrote:
> 
> 
> 
> 
> I am having trouble understanding how a character is sent
> to the lcd 
> display by way of at-keybd. I am using stk500 with 8515
> mcu and 4x20 
> lcd. I am using portd-pd2(int0) for clock and pd5(oc1a)
> for data. My 
> question is,do I need a pysical connection from 8515 to
> lcd in order 
> to pass data to lcd or is this passed by way of software
> code. My lcd 
> is wired using porta and is currently working. I just
> want to grasp
> an 
> understand of the flow of data from keybd to lcd. Is the
> uarts 
> transmit data out pin pd1 used(hardwired) or is it just
> coded via 
> software to send data stored in registers and transmitted
> out to lcd. 
> Is this what is meant by (softuart) or am I missing
> something here. 
> Any help would be appreciated. 
> 
SoftUART means that the uart function is implemented in
code, doing what the usual UART registers and shifters do.
UARTs are used to receive and transmit asynchronous
characters (start-bit and stop-bit scheme). Normally, when
you communicate with an LCD display, a UART is not used
(that said, tbere are a FEW LCD displays with asynch I/O).
Usually, every logic-state change of the interface to/from
the LCD is handled in direct software. But, its not
asynchronous, so it is not a UART.

Jim
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