AVR-Chat

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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