Second UART on BB-XM

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1

Hi,

I'm working on connecting my beagleboard to another device over UART.
However, that device will only work with TTL logic.
So my question is: What is the voltage level of the second UART on the
expansion header of a BeagleBoard XM?
Also, with Angstrom, do I need to change some PINMUX settings to use
it?
I'm using a console-only build from Narcissus.

Cheers,
Akhil

2

The Beagleboard-xM system reference manual states (http://beagleboard.org/static/BBxMSRM_latest.pdf):

“CAUTION: The voltage levels on the expansion header are 1.8V. Exposure of these signals to a higher voltage will result in damage to the board and a voiding of the warranty.”

So, you will need a voltage level translator. This one might work: http://www.sparkfun.com/products/8745

3

Thanks Jake for the quick reply!
I bought a USB to TTL serial converter suspecting this.
The idea was to get something that will allow me to use a PC or the
beagleboard.

The problem is, its a CP2102 chip which doesn't work with Angstrom.
I tried compiling the drivers given here:
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx

I get the following error while building directly at my BeagleBoard:
make -C /lib/modules/2.6.32/build -I /media/sda1/cp210x-3.1.0/cp210x
M=/media/sda1/cp210x-3.1.0/cp210x modules
make: *** /lib/modules/2.6.32/build: No such file or directory. Stop.
make: *** [modules] Error 2

Any ideas?

4

Why don't you just rebuild the kernel with?

CONFIG_USB_SERIAL_CP210X

Support for the CP210x usb-serial devices has been mainline for awhile..

Regards,

5

Thanks Robert. I'll try that.

6

Hi,

I tried rebuilding the kernel.

1. First, I followed the steps here:
http://www.angstrom-distribution.org/building-angstrom
and built an un-modified kernel.

2. Uncommented the CONFIG_USB_SERIAL_CP210X line like:
CONFIG_USB_SERIAL_CP210X=m

3. Did a clean:
MACHINE=beagleboard ./oebb.sh clean

4. Copied the uImage file to the boot partition, made a backup of the
firmware and modules folders in /lib, deleted them and extracted the
modules archive there.

I got a new shiny 3.0 kernel but still no CP210x support! There's no /
dev/ttyUSB0 upon inserting the device.
Any pointers on what I did wrong?

Cheers,
Akhil

7

Finally got round to working on this again.
I copied the vmlinux file to /boot and it works now.
I wonder why this is not part of the deploy folder.