Olimex Support Forum

OLinuXino Android / Linux boards and System On Modules => A13 => Topic started by: bruceuk on November 12, 2014, 02:58:05 PM

Title: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: bruceuk on November 12, 2014, 02:58:05 PM

Has anybody attempted something similar? The A13-SOM is unfortunately limited to a single UART3, hoping somebody else has tried extending via an I2C-UART Bridge IC?

I can't find any Linux kernel drivers for such an IC so I assume the design is overly complicated?

Examples of I2C-UART:
http://www.nxp.com/products/interface_and_connectivity/bridges/i2c_spi_slave_to_uart_irda_gpio_bridges/

http://www.nxp.com/documents/brochure/75017552.pdf

Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: Gerrit on November 12, 2014, 04:23:53 PM
there is linux driver for SPI MAX3110

http://cateee.net/lkddb/web-lkddb/SERIAL_MRST_MAX3110.html

but i guess an USB solution is more easy to implement cheap and some come with a similar interface as the board like

http://www.dx.com/p/usb-2-0-to-ttl-uart-5-pin-cp2102-module-serial-converter-blue-152317
http://www.miniinthebox.com/cp2102-usb-2-0-to-ttl-uart-6pin-module-serial-converter_p391022.html
https://www.olimex.com/Products/Components/Cables/USB-Serial-Cable/USB-Serial-Cable-M/

or direct to rs232 http://www.tinydeal.com/usb-to-rs232-adapter-p-2435.html



Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: bruceuk on November 25, 2014, 03:38:56 PM

I guess nobody else needs more UARTS :(

I found this:
http://www.maximintegrated.com/en/products/interface/controllers-expanders/MAX14830.html

Sadly I can't find any "break out" board in order to test the kernel driver. I believe the mainline kernel does support it so.....maybe have to take a chance and add it to my board and hope it works.
Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: JohnS on November 25, 2014, 04:56:10 PM
A13 looks to have more uarts than others need so yes you're probably the only one.

John
Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: bruceuk on November 26, 2014, 01:24:51 PM

John, little confused by your comment:

"..A13 looks to have more uarts..."
You mention uarts (plural) ...but I can only see one?

The A13 processor as 3 uarts (uart0, uart1 & uart3)

uart0 share pins with sdco and is therefore used by the sdcard
uart1 is used for the console/debug port
uart3 is available ...provided you don't need spi1

So the A13-SOM has a single uart available

What have a missed? ... I'm new to board level electronics so please feel free to critique the above thinking.

Thanks
Bruce




Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: JohnS on November 26, 2014, 02:35:40 PM
It's got multiple uarts so I just said what's true.  Many/most people aren't already using them as you in effect say you are.  I suspect most people have no use at all for uarts nowadays let alone for more than one.

If you need even more then add them.  There are USB, etc boards that are very cheap.

John
Title: Re: A13-SOM: Adding additional UART via I2C UART Bridge IC?
Post by: bruceuk on November 26, 2014, 04:18:41 PM

ok...got it, thanks for explaining ...wanted to be sure I understood so had to ask.