On Aug 1, 10:44 am, "dkel...@hotmail.com" <dkel...@hotmail.com> wrote:
> On Jul 31, 3:11 pm, Eric <ericjohnholl...@hotmail.com> wrote:
>
>
>
> > 16550 UART Initialization Routine
>
> > I'm having a little trouble trying to get my 16550 to Receive
> > Characters. I can get it to transmit Bytes, but it will not receive
> > bytes.
>
> > My Initialization Routine is as follows:
> > LCR=0x80; // Set Baud Rate Divisor Latch to 1
> > DLM=0x00; // Set Baud Rate divider
> > DLL=0x1b;
> > LCR=0x03; // Set Divisor Latch to 1 and 8bit word length
> > MCR=0x00;
> > FCR=0x07; //Enable FIFOs and Reset the RX & TX FIFO. Set FIFO trigger
> > level to 1 byte
> > IER=0x0F; // Enable all Interrupts
>
> > THR=0x30; // This transmits "0" ASCII character
>
> > when I read the RBR register I always get 0x00 when I know I sent
> > characters to the port.
>
> > Any thoughts would be helpful.
>
> > Thanks,
>
> > Eric
>
> Hi
>  You enable interrupts?? Why if you intend to read the port. It might
> be that the interrupt routine is reading your input before you get
> there.
> Also, are you waiting long enough for the loopback?
>  Are you even looking at a loop back? Why would you expect
> a sent character to be in the receive buffer??
> Dwight


Hi
 I missed one. Why are you setting MCR to 0 ???
Dwight

On Jul 31, 3:11 pm, Eric <ericjohnholl...@hotmail.com> wrote:
> 16550 UART Initialization Routine
>
> I'm having a little trouble trying to get my 16550 to Receive
> Characters. I can get it to transmit Bytes, but it will not receive
> bytes.
>
> My Initialization Routine is as follows:
> LCR=0x80; // Set Baud Rate Divisor Latch to 1
> DLM=0x00; // Set Baud Rate divider
> DLL=0x1b;
> LCR=0x03; // Set Divisor Latch to 1 and 8bit word length
> MCR=0x00;
> FCR=0x07; //Enable FIFOs and Reset the RX & TX FIFO. Set FIFO trigger
> level to 1 byte
> IER=0x0F; // Enable all Interrupts
>
> THR=0x30; // This transmits "0" ASCII character
>
> when I read the RBR register I always get 0x00 when I know I sent
> characters to the port.
>
> Any thoughts would be helpful.
>
> Thanks,
>
> Eric


Hi
 You enable interrupts?? Why if you intend to read the port. It might
be that the interrupt routine is reading your input before you get
there.
Also, are you waiting long enough for the loopback?
 Are you even looking at a loop back? Why would you expect
a sent character to be in the receive buffer??
Dwight

16550 UART Initialization Routine

I'm having a little trouble trying to get my 16550 to Receive
Characters. I can get it to transmit Bytes, but it will not receive
bytes.

My Initialization Routine is as follows:
LCR=0x80; // Set Baud Rate Divisor Latch to 1
DLM=0x00; // Set Baud Rate divider
DLL=0x1b;
LCR=0x03; // Set Divisor Latch to 1 and 8bit word length
MCR=0x00;
FCR=0x07; //Enable FIFOs and Reset the RX & TX FIFO. Set FIFO trigger
level to 1 byte
IER=0x0F; // Enable all Interrupts

THR=0x30; // This transmits "0" ASCII character

when I read the RBR register I always get 0x00 when I know I sent
characters to the port.

Any thoughts would be helpful.

Thanks,

Eric