make my way: május 2012

2012. május 26., szombat

Házisárkány

2012. május 25., péntek

Power consumption of the Realtek 8192CU based USB wireless adapter

Under Linux, the Realtek 8192CU based USB wireless adapter has a beacon based management for power savings. When it is set to maximum (kernel module parameter rtw_power_mgnt), the adapter answers only every third beacon packet of the wireless router. I have the following observations with my router:

- Setting the beacon interval of the router: it does not effect the power consumption of the wireless adapter.
- Setting the power management to minimum (rtw_power_mgnt=1): the adapter consumes: 0.5-1.0 W in idle.
- Setting the power management to maximum (rtw_power_mgnt=2): the adapter consumes: 1.0-1.5 W in idle.

Verdict: it is the best to use the power management to set to minimum. The maximum "power saving" consumes more energy (by 0.5 W) significantly.

Symbian Anna/Belle development with Qt Creator under Ubuntu Linux (Developing for a dead platform)

It is fairly easy, but underdocumented:

1. Download testinstaller_scp1.2_v201109280000_241.x32.7z and install from http://projects.developer.nokia.com/symbian_linux_qtsdk.
2. Copy and install public_coda_installer_1-0-5_build2_signed.sis from the Qt Creator installation (QtSDK/Symbian/sis/Symbian^3/CODA) to the Symbian phone.
3. Connect the mobile phone and a computer to a WLAN network.
4. Run the CODA on the phone, go to its settings, select the WLAN mode and start it. The IP address and the debug port are shown in CODA.
5. Create a project in Qt Creator, select the Symbian target.
6. Go to Projects/Symbian device/Run settings/Deployment and set the IP address+port from the phone in the WLAN field (e.g 192.168.20.13:1534).
7. Add the following code to the main.cpp, otherwise, you get an instant crash (at least on N9/Symbian Anna):

static CTrapCleanup *tc = CTrapCleanup::New();

8. Run the project on the device and enjoy!