Tag Archives: usb

Getting started with the Arietta G25 board

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This weekend, I received my ACME Arietta G25 Atmel ARM board, and tried to get it going with my Mac. I ordered the “plain” version with 128 MB RAM, as well as one with 256MB RAM, as well as Wifi boards and the DPI debug board.

After soldering in the necessary posts, I attached the DPI board and verified that my Mac has the right FT232 driver to access the console, no problems here.

I then fired up by Ubuntu VirtualBox machine and followed the instructions to build the Micro-SD-Card image. I then proceeded to boot successfully from the card.

IMG_2989

Through the console, I could get the Wifi card going; since I wanted to have support for more than a single network, I extended the configuration through wpa_supplicant.conf.

ACME has configured a Gadget driver to supply an Ethernet interface through the host port on the Arietta; in ACMEs configuration, this is set to offer both RNDIS and CDC EEM modes. Unfortunately, Mac OS X 10.9 doesn’t support either.

After some more reading, I decided to build my own kernel and modules. To get a Mac-compatible setup for the USB Gadget driver, run menuconfig, and navigate to

  • Device Drivers
  • USB support
  • USB Gadget Support (at the very bottom of the list)

For Mac compatibility, de-select the RNDIS support and the Ethernet Emulation Model (EEM) support under Ethernet Gadget.

I also chose to enable the Serial Gadget and the CDC Composite De
vice (Ethernet and ACM).

After building the kernel and replacing the files on the SD Card, I changed the module load line in /etc/network/interfaces to load the g_cdc module instead of the g_ether module, and added an entry in /etc/inittab for /dev/ttyGS0 to also have a console through the host port.

Booting from an USB disk – even when your system doesn’t support it

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I like using VMware Fusion on my Mac, but it has one shortcoming: it cannot boot from USB devices. You can use disk images (floppy, CD/DVD and harddisk) as well as a physical optical drive, but USB devices are not available. That’s unfortunate if you want to use VMware to prepare a hard disk for a machine, and want to test booting off that system before installing it in the machine.

When I install a new FreeBSD machine, I often start out from an existing FreeBSD machine and install directly from that running system, instead of booting off an install DVD. Obviously, using a virtual machine for this bootstrapping system, together with a USB hard disk adapter, is very convenient. But without being able to boot the VM off that USB disk, testing can be cumbersome.

I was very happy to come across Plop, a boot manager with many features. The most interesting one for me is it’s support for booting off USB devices without BIOS support. Plop includes its own U/O/EHCI driver, supporting standard USB 1.1 and USB 2.0 devices and ports.

Also very important: Plop can be run off a CD or floppy image, so you don’t need to (re-)configure your main hard disk. If I feel adventurous, I might look into patching the Plop BIOS extension into VMware, making booting even easier. For the time being, I’m using the floppy image, since none of my virtual (nor physical) machines have floppy drives any more.

Also, when you have an older machine which BIOS does not support booting off USB devices, Plop might be very helpful!

TEMPer USB Thermometer

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Measuring temperature in a PC should be easy: after all, most mainboards have extensive monitoring capabilities for temperature and voltage levels built-in. Unfortunately, very few of these facilities are documented properly, and software support is lacking. Instead of trying to navigate the maze that is lm-sensors (which isn’t even available for FreeBSD), I decided to look for some USB-based solution.

There’s a reasonably cheap chinese USB thermometer called TEMPer. I got mine from Brando for 12 Euros. It’s a USB-to-serial chip from WinChipHead. It’s DTR, RTS, and CTS lines are used to connect a LM75 I²C temperature sensor. To talk to the LM75, you need some bit-banging driver.

I’ve put together a command line utility for the TEMPer that can program the built-in thermostat (TEMPer has a LED connected to that output) and print out temperature measurement data. It does it’s job, and might serve as an example on how to do I²C over a simple interface.

FreeBSD ppp(8): work around invalid remote address

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When connecting via a Huawai E169 UTMS USB stick through O2 Germany’s network, the data stick or the network suggests a PPP IPCP remote address of 0.0.0.0. FreeBSD refuses to ifconfig the tun interface with this endpoint address.

Fortunately, ppp(8) offers a configuration parameter to influence the IP addresses negotiated with the peer (ifaddr), and suggesting a different address will make the configuration work.

If you get this log output from ppp, you need to configure address selection:

IPCP: deflink: RecvConfigAck(4) state = Req-Sent
IPCP:  IPADDR[6] 10.68.235.57
IPCP:  PRIDNS[6] 193.189.244.197
IPCP:  SECDNS[6] 193.189.244.205
IPCP: deflink: State change Req-Sent --> Ack-Rcvd
IPCP: deflink: RecvConfigReq(47) state = Ack-Rcvd
IPCP:   [EMPTY]
IPCP: deflink: SendConfigAck(47) state = Ack-Rcvd
IPCP:   [EMPTY]
IPCP: deflink: State change Ack-Rcvd --> Opened
IPCP: deflink: LayerUp.
IPCP: myaddr 10.68.235.57 hisaddr = 0.0.0.0
Warning: iface add: ioctl(SIOCAIFADDR, 10.68.235.57 -> 0.0.0.0): Destination address required
Error: ipcp_InterfaceUp: unable to set ip address

Here’s my complete ppp.conf, with the ifaddr line included:

u3g:
	set device /dev/cuaU0.0
	set speed 115200
	set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0
	set authname internet
	set authkey  internet
	set log local phase ipcp
	set dial "ABORT BUSY TIMEOUT 2 \
		\"\" \
		AT OK-AT-OK \
		AT+CFUN=1 OK-AT-OK \
		AT+CMEE=2 OK-AT-OK \
		AT+CSQ OK \
		AT+CGDCONT=1,\\\"IP\\\",\\\"internet\\\" OK \
		AT+CGACT? OK-AT-OK \
		AT+CGATT? OK \
		AT+CGCLASS? OK \
		AT+COPS? OK \
		ATD*99***1# CONNECT"
	set crtscts on
	nat enable yes
	add default HISADDR
	disable dns

This applies to both 7-stable and 8-stable (with both the old and the new USB stacks). I’ve used u3g(4) on both occasions. The original ppp.conf for 3G modems is based off this one from Nick Hibma.

This is how it looks like when using ifaddr:

IPCP:  PRIDNS[6] 10.11.12.13
IPCP:  SECDNS[6] 10.11.12.14
IPCP:  PRINBNS[6] 10.11.12.13
IPCP: MS NBNS req 130 - NAK??
IPCP:  SECNBNS[6] 10.11.12.14
IPCP: MS NBNS req 132 - NAK??
IPCP: deflink: SendConfigReq(2) state = Req-Sent
IPCP:  IPADDR[6] 10.0.0.1
IPCP:  COMPPROTO[6] 16 VJ slots with slot compression
IPCP: deflink: RecvConfigReq(50) state = Req-Sent
IPCP:   [EMPTY]
IPCP: deflink: SendConfigNak(50) state = Req-Sent
IPCP:  IPADDR[6] 10.0.0.2
IPCP: deflink: RecvConfigRej(2) state = Req-Sent
IPCP:  COMPPROTO[6] 16 VJ slots with slot compression
IPCP: deflink: SendConfigReq(3) state = Req-Sent
IPCP:  IPADDR[6] 10.0.0.1
IPCP: deflink: RecvConfigNak(3) state = Req-Sent
IPCP:  IPADDR[6] 10.42.237.110
IPCP:  IPADDR[6] changing address: 10.0.0.1  --> 10.42.237.110
IPCP: deflink: SendConfigReq(4) state = Req-Sent
IPCP:  IPADDR[6] 10.42.237.110
IPCP: deflink: RecvConfigAck(4) state = Req-Sent
IPCP:  IPADDR[6] 10.42.237.110
IPCP: deflink: State change Req-Sent --> Ack-Rcvd
IPCP: deflink: RecvConfigReq(51) state = Ack-Rcvd
IPCP:   [EMPTY]
IPCP: deflink: SendConfigAck(51) state = Ack-Rcvd
IPCP:   [EMPTY]
IPCP: deflink: State change Ack-Rcvd --> Opened
IPCP: deflink: LayerUp.
IPCP: myaddr 10.42.237.110 hisaddr = 10.0.0.2
PPP ON freebsd-current>