Powering the Demo Board off of USB Power during debugging
WBA Consulting
Posts: 2,935
Is anyone aware of any concerns I should have if I modify the Propeller Demo Board to make use of the 5 volts present on the USB bus? I would like to be able to run programs during debugging without worrying about external power. My plan was to run a jumper from USB5V over to a 2 pin header that is attached to the demo board's 5V bus. If I attach a jumper shunt on the header, that would bridge USB 5V over to the Prop's power.
Since a USB port can deliver 500mA (per spec) and can be paired with a second port to provide 1A, the supply should run the demo board nicely. I am not sure if the FTDI chip will advise windows of it's power needs and have windows limit the current on the port it is attached to.
Also, the Power Supply Chart on the website doesn't list any recommendations for the Prop. This may be due to the fact that the prop is so versatile, the range of current needed is heavily dependent on your program/design?
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Andrew Williams
WBA Consulting
IT / Web / PCB / Audio
Post Edited (WBA Consulting) : 8/12/2009 9:34:58 PM GMT
Since a USB port can deliver 500mA (per spec) and can be paired with a second port to provide 1A, the supply should run the demo board nicely. I am not sure if the FTDI chip will advise windows of it's power needs and have windows limit the current on the port it is attached to.
Also, the Power Supply Chart on the website doesn't list any recommendations for the Prop. This may be due to the fact that the prop is so versatile, the range of current needed is heavily dependent on your program/design?
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Andrew Williams
WBA Consulting
IT / Web / PCB / Audio
Post Edited (WBA Consulting) : 8/12/2009 9:34:58 PM GMT
Comments
How do you propose to balance the power per port?
-Phil
I think I will just make a USB cable that will utilize two USB ports. One port will be for the FTDI (4 wires) and the other port will only be used to draw +5 (2 wires). This way I don't have to worry about the current limitation driven by the FTDI's enumeration.
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Andrew Williams
WBA Consulting
IT / Web / PCB / Audio
http://www.rayslogic.com/propeller/Programming/RaysStuff/Crystal.JPG
(also shows·a 6.25 MHz crystal for 100 MHz)
It maybe a little dangerous, but I like to live on the edge!
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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm