external serial UARTS on 8250/16C550/16C554/16C654

Dear all,

I have plan to add 4 additional UARTs into the Linux system based on the AT91SAM9 MCU (Stamp9G20 or PortuxG20).

1. Can somebody give me some hints how to connect one of the TL16C2550, 16C554, 16C550, 16C654 UARTs? Of course full solution or partial (part of schematic and/or Linux driver) will be very appreciated.

2. Does it required to connect all interrupt and CS lines to individual pins of MCU or some of them can be shared?

3. As I understand, it is required to add a new driver like a 8250_accent.c or 8250_exar_st16c554.c? But what is confusing for me is that AT91SAM9 does not use port accesses to devices connected through SMC - it uses MMIO. How to deal with this in the driver?

Best regards!
--
Igor Plyatov

Re: external serial UARTS on 8250/16C550/16C554/16C654

Hi,

The AT91.. provides a couple of serial ports already, are these not enough for your application?

Kees

Re: external serial UARTS on 8250/16C550/16C554/16C654

Yes, its not enough. We need to adapt an old device which requires many UARTs, but AT91SAM9G20 can provide only 6.

Re: external serial UARTS on 8250/16C550/16C554/16C654

Why not use USB/Serial adapter ?

Winfried

Re: external serial UARTS on 8250/16C550/16C554/16C654

Hi Igor,

from my own experience I can tell that it is far from trivial connecting to the bus lines of the MCU of the stamp. For my own part, I tend to use parts connected via I²C or SPI rather than share the MCU bus.

IIRC, Maxim offers an SPI UART (MAX3100 ..?). I don't know if there's drivers for this one available, but it could well solve your problems while greatly reducing the number of MCU lines involved!

I hope you will find a perfect solution!

Nick

Syndicate content