On 7/22/05, Tim Wade <tim.wade@....au> wrote:
> Hi
>
> I really wouldn't blame the LPC -- it is very likely that the PC is
> loosing the characters...
>
> We had a FAST PC logging data coming from a GPS receiver at 56K, so not
> very fast really, but come hell nor high water we could NOT get the PC
> to collect all the characters. Eventually we got a HIGH QUALITY
> USB<=>RS232 interface and that worked fine... Windows is NOT very real
> time at all... In fact it is almost completely useless for any sort of
> time constrained operation at all. Just because it is popular does not
> mean that it works very well...
>
>
>
>
> -----Original Message-----
> From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com] On Behalf
> Of Mohan K
> Sent: Friday, 22 July 2005 11:45 AM
> To: lpc2000@yahoogroups.com
> Cc: ph@...
> Subject: Re: [lpc2000] More UART woes
>
> Hi all/PH,
> I am also facing the same problem.
> When I try to send the 8+Kbytes of data, on the other end am loosing
> some bytes. The speed of transmission is 115200kbps. The driver uses a
> circular buffer for transmission. Following is the code used to transfer
> 8Kbytes of data:
>
> int uart1Putch(int ch)
> {
> //#ifdef UART0_TX_INT_MODE
> uint16_t temp;
> // unsigned cpsr;
> temp = (uart1_tx_insert_idx + 1) % UART1_TX_BUFFER_SIZE;
> if(temp == uart1_tx_extract_idx)
> return -1; // no room
> //cpsr = disableIRQ(); // disable global
> interrupts
> U1IER &= ~UIER_ETBEI; // disable TX interrupts
> //restoreIRQ(cpsr); // restore
> global
> interrupts
> // check if in process of sending data
> if(uart1_tx_running)
> {
> // add to queue
> uart1_tx_buffer[uart1_tx_insert_idx] =
> (uint8_t)ch;
> uart1_tx_insert_idx = temp;
> }
> else
> {
> // set running flag and write to output register
> uart1_tx_running = 1;
> U1THR = (uint8_t)ch;
> }
> //cpsr = disableIRQ(); // disable global
> interrupts
> U1IER |= UIER_ETBEI; // enable TX interrupts
> //restoreIRQ(cpsr); // restore
> global
> interrupts
> return (uint8_t)ch;
> }
>
> Am i missing anything? Please advice me.
>
> Thanks & Regards,
> Mohan
>
>
>
>
> On 7/21/05, vajper0 <ph@...> wrote:
> > Still working on my UART driver for the LPC2138. Now I'm having
> > problems with lost Tx data from the LPC to a PC. I don't have a clue
> > about what I'm doing wrong and I haven't found anything on the web
> > indicating this is a common problem.
> >
> > The problem is that sometimes one or a few bytes that I write to the
> > THR don't show up at the PC. If there is data to be transmitted I
> > write one byte to the THR (first checking the LSR5 to be really shure
> > there is room for a byte). Then I write 16 bytes to the THR every
> > time I get a THR IRQ (also here checking LSR5 to be 100% sure the FIFO
>
> > is empty).
> >
> > Doing the above results in lost data at the other end. This happens
> > approximately every 20-50kbytes. I've tried this at different speeds,
> > even as low as 57600bps. The FIFOs are enabled.
> >
> > Am I missing something?
> >
> > /PH
> >
> >
> >
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