wraggster
September 4th, 2012, 23:50
http://hackadaycom.files.wordpress.com/2012/09/problems-powering-rpi-from-gpio-e1346770119365.jpg
[Zaion] grabbed an ATX power supply to source the 5V the Raspberry Pi needs to run. The common problem when it comes to RPi supplies is a shortfall in how much current a USB wall adapter can source. The ATX shouldn’t have this problem, but none-the-less he found that the USB ports were only reading about 5V. Strange. He grabbed the soldering iron and fixed the issue with a piece of jumper wire (http://www.digitalexperience.eu/site/hw/aggiungere-connessione-wifi-al-raspberry-pi-e-dintorni) (English translation found in the second half of his post).
The problem was discovered when trying to get a WiFi dongle to work on one of the RPi’s USB ports. It simply wouldn’t show up, and after going down the blind alley of assuming it was a driver problem he started to investigate the hardware. After discovering the below-nominal voltage [Zaion] measured the resistance between the 5V pin on the GPIO header and the one on the USB port. It reads 3-4 Ohms and he concluded that the trace is too thin. We took a quick look at the schematic for the board (http://www.raspberrypi.org/archives/1090)and see no reason for the voltage drop. His jumper wire fixed the issue but it leaves us wondering, is this an isolated case, or a design flaw? Tell us what you think in the comments section.
http://hackaday.com/2012/09/04/problems-powering-raspberry-pi-from-gpio-header/
[Zaion] grabbed an ATX power supply to source the 5V the Raspberry Pi needs to run. The common problem when it comes to RPi supplies is a shortfall in how much current a USB wall adapter can source. The ATX shouldn’t have this problem, but none-the-less he found that the USB ports were only reading about 5V. Strange. He grabbed the soldering iron and fixed the issue with a piece of jumper wire (http://www.digitalexperience.eu/site/hw/aggiungere-connessione-wifi-al-raspberry-pi-e-dintorni) (English translation found in the second half of his post).
The problem was discovered when trying to get a WiFi dongle to work on one of the RPi’s USB ports. It simply wouldn’t show up, and after going down the blind alley of assuming it was a driver problem he started to investigate the hardware. After discovering the below-nominal voltage [Zaion] measured the resistance between the 5V pin on the GPIO header and the one on the USB port. It reads 3-4 Ohms and he concluded that the trace is too thin. We took a quick look at the schematic for the board (http://www.raspberrypi.org/archives/1090)and see no reason for the voltage drop. His jumper wire fixed the issue but it leaves us wondering, is this an isolated case, or a design flaw? Tell us what you think in the comments section.
http://hackaday.com/2012/09/04/problems-powering-raspberry-pi-from-gpio-header/