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QuickStart doesn't like AC adapters — Parallax Forums

QuickStart doesn't like AC adapters

localrogerlocalroger Posts: 3,452
edited 2012-04-16 13:32 in Propeller 1
...or car adapters. I had been planning to deploy several quickstarts for a simple application and power them from mini-USB charger warts. All units work fine on the programming cable, but none work on any of the wall warts. I finally took one out to the car and tried my GPS charging cable, it doesn't work either. The cables are putting out the same 5V as a USB port and the green LED comes on, but not very bright, and the Propeller is undervoltaged at about 2.5V. I see there is a transistor between USB-5V and Vin, but it's not clear why this is misbehaving. Anybody have a solution?

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-16 13:12
    You need to ground one of the pins on the QS for power only USB cables.

    Pin 30 (I think), /USB_PWR.
  • photomankcphotomankc Posts: 943
    edited 2012-04-16 13:13
    There is something about that in the datasheet for it. Can't pull it off the top of my head but the QS negotiates with USB for the power and follows the protocol so if it's a dumb charger it won't work but there is a pin that is used to tell it to go on without the handshake over USB and just use the power. I'll bet that's your issue.
  • localrogerlocalroger Posts: 3,452
    edited 2012-04-16 13:32
    Jumping 30 to 39 got it. Thanks guys.
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