LPC2138 UART0/1 and modem control

Started by czajniczek December 20, 2005

Hi !

I'm about to build a system using LPC2138. It's going to be equipped
with RS232C and RS485 ports. As I need full RS232 implementation with
modem control lines, I will use UART1 for it, and UART0 for RS485 in
turn.

Unfortunately I'd like to use serial ISP programming, which uses
UART0, and I don't like an idea of flashing through RS485.

After reviewing the manual I've got an idea of using UART0's TX/RX
with UART1's modem control lines for RS232, and UART1 TX/RX for RS485.
Modem control, and actual serial interface for UART1 seem quite
independent.

Any other ideas ?

Regards,
Przemyslaw


An Engineer's Guide to the LPC2100 Series

Hi Przemyslaw,

take a look at MAX3160E-Interface, I use it in my design with RS232 serial
ISP and switch to RS485 afterwards.

Thomas lpc2000@lpc2... wrote on 20.12.2005 16:43:13:

>
> Hi !
>
> I'm about to build a system using LPC2138. It's going to be equipped
> with RS232C and RS485 ports. As I need full RS232 implementation with
> modem control lines, I will use UART1 for it, and UART0 for RS485 in
> turn.
>
> Unfortunately I'd like to use serial ISP programming, which uses
> UART0, and I don't like an idea of flashing through RS485.
>
> After reviewing the manual I've got an idea of using UART0's TX/RX
> with UART1's modem control lines for RS232, and UART1 TX/RX for RS485.
> Modem control, and actual serial interface for UART1 seem quite
> independent.
>
> Any other ideas ?
>
> Regards,
> Przemyslaw



Do you mean attaching this chip to UART0 for RS232 ISP and RS485 for normal operation, leaving UART1 for full RS232 ? Here comes another diffculty - I will need optical isolation on RS485. But anyway this is a possible solution, thanks !

Still, does anybody know if UART1 modem control circuitry is in any way dependant on UART1 itself ?
It seems to be a separate hardware.

> take a look at MAX3160E-Interface, I use it in my design with RS232 serial
> ISP and switch to RS485 afterwards.
>
> Thomas
>
> > I'm about to build a system using LPC2138. It's going to be equipped
> > with RS232C and RS485 ports. As I need full RS232 implementation with
> > modem control lines, I will use UART1 for it, and UART0 for RS485 in
> > turn.
> >
> > Unfortunately I'd like to use serial ISP programming, which uses
> > UART0, and I don't like an idea of flashing through RS485.



Hi,

I'd like to use the Max3160. I've been quoted AU$8.50 for the part. :-(

Instead I use an ST232 @ AU$2.90 and a MAX3189 @ AU$2.28, plus a 3pin jumper
to select the RX line between the 2.

It's not ideal, but the Max3160 is SO expensive.

Cheers,

Peter.

thomas.kuschel@thom... wrote:
> Hi Przemyslaw,
>
> take a look at MAX3160E-Interface, I use it in my design with RS232 serial
> ISP and switch to RS485 afterwards.
>
> Thomas > lpc2000@lpc2... wrote on 20.12.2005 16:43:13: >>Hi !
>>
>>I'm about to build a system using LPC2138. It's going to be equipped
>>with RS232C and RS485 ports. As I need full RS232 implementation with
>>modem control lines, I will use UART1 for it, and UART0 for RS485 in
>>turn.
>>
>>Unfortunately I'd like to use serial ISP programming, which uses
>>UART0, and I don't like an idea of flashing through RS485.
>>
>>After reviewing the manual I've got an idea of using UART0's TX/RX
>>with UART1's modem control lines for RS232, and UART1 TX/RX for RS485.
>>Modem control, and actual serial interface for UART1 seem quite
>>independent.
>>
>>Any other ideas ?
>>
>>Regards,
>>Przemyslaw >
>
> Yahoo! Groups Links >
>

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