Portable Power for PropellerQuickstart board?
I have an application that requires battery power for a QuickStart board---40000, Revision B. I have 3V and 6V battery power available.
Applying +6V power alone (no USB signals) to the QuickStart board through the USB socket's power pins does not work. The Parallax designer has used the CBUS-0 and the CBUS-3 output pins from the FTDI231 USB-interface chip to control the current flow through the AP1117 voltage regulator. I have no insight into why the designer did this. The QS board has a Vin connection that goes directly to the voltage-regulator IC. This signal also goes to pin 40 on the 40-pin interface board, so that might provide a work-around; that is, apply 6V to the Vin pin. But before I apply 6V to the Vin contact I'd like to hear from someone at Parallax--or someone with experience battery powering the QS board.
I still need an operating USB interface so people can do field updates of software.
Any ideas are greatly appreciated. Thanks. --Jon
I've attached a PDF with the schematic for the QuickStart (40000, Rev , the schematic on page 3 shows the power circuit. I also have the Diptrace schematic file, let me know if you want a copy of that file.
Here is also some power information I obtain previously from the forum:
You can use an external USB Battery pack and your normal USB cable to run a
Quick Start Board, but you will need to use a jumper to Ground (Vss)
Pin 30 (USB_PWR_EN) on the Header connector in order for the onboard power
supply circuit to turn-on.
I just did this experiment on one of my Quick Start Rev A Boards, and it
powered up and ran its stored program as normal. As far as I can tell from the
schematics, this should also work on the Quick Start Rev B boards too.
NOTE: BE SURE TO REMOVE THE JUMPER FROM PIN 30 BEFORE
CONNECTING THE QUICK START BOARD TO YOUR PC
TO PREVENT DAMAGE TO THE BOARD.
It is also possible to power the Quick Start board externally via
pins/pads 39 and 40 of J1 or J3.
Thanks, Francis. I appreciate your reply and will give it a try. I see pin 30 and can follow it on the schematics. That's a big help. --Jon
The FT231x is configured so that the QuickStart only draws power when USB specifications allow it, but if that isn't a concern for your application, you can use FTDI's FT_PROG utility to change the behavior of the CBUS pins, so that power is always enabled. Driving either one low will do the trick, or you can do so externally, without changing the configuration, by grounding the /USB_PWR_EN pin, labeled "/UPE" on the 40-pin header. You could also connect the 6-volt power supply to the "Vin" pin on the header, and it will power the QuickStart, regardless of the state of the USB port and its signals.
@"David Carrier" we should indicate here that this is more relevant for later model versions of this board. For my proof of concept for one I promptly stuck headers on the unpopulated power places on the board and found that it worked.
Now why is a crowd of robots leaving one place in CA along Highway 99 to go to another after visiting a certain town that means something wrong in Greek? Also no mascot he's away this month.