Contents - Raspberry PI Community Projects

Ethernet connects at 10M instead of 100M
The LED in the corner of the board labelled "10M" is mislabeled. When that LED is on,
the R-Pi is actually connected at 100 Mbps. You can confirm the true transfer rate using a
network benchmark such as iperf. You can also read the current network speed with
cat /sys/class/net/eth0/speed
Cannot ssh in to Pi
In the Debian image, ssh is disabled by default. Boot commands are taken from /boot/
boot.rc if that file present. There is an example file named boot_enable_ssh.rc that
enables ssh. So:
sudo mv /boot/boot_enable_ssh.rc /boot/boot.rc
and reboot should enable ssh. (password as below)
Network/USB chip gets too hot to touch
This is normal. In open air at 24 C, the LAN9512 Ethernet/USB chip reaches about 52 C
after some time. This is too hot to touch for more than a few seconds, but it is not
unusually hot for the chip.
The LAN9512 data sheet (http://www.smsc.com/media/Downloads_Public/Data_Sheets/
9512.pdf) in Table 4.1 on p.40 says it comes in two versions, rated for operation at an
ambient temperature in still air (Ta) of 70 C (commercial) or 85 C (industrial). It uses 763
mW at 3.3V with maximum traffic on 100baseT and both USB ports (Table 4.3.4, p. 42).
There is a study of RasPi heat profiles by "Remy" at ¿Se calienta el ordenador Raspberry
Pi? Estudio de sus temperaturas en funcionamiento (http://www.geektopia.es/es/
technology/2012/06/22/articulos/se-calienta-el-ordenador-raspberry-pi-estudio-de-sustemperaturas-en-funcionamiento.html)
(Is the Raspberry Pi computer getting hot? A
study of its operational temperature.) The Spanish article has numerous color
temperature images of RasPi in various operational modes, with the highest LAN9512
case temperature measured as 64.5 C.
Networking no longer works when changing SD card between two
Raspberry Pis
In some distributions, /etc/udev/rules.d/70-persistent-net.rules remembers which MAC
address is associated with eth0, so each new device will be assigned as a different
interface (eth1, eth2, etc.) due to the different MAC addresses. Editing /etc/udev/rules.d/