My advice is to read the System Reference Manual. It will save you a lot of heartache.
Gerald On Tue, Mar 24, 2015 at 11:14 AM, Khalil Estell <[email protected]> wrote: > Thank you Graham. That clears a lot of stuff up for me. It just so happens > that I am using 8 of the LCD data pins for my shield without knowing about > how loading those pins down can result in a disturbance in the booting > process. Since I was not using an LCD, I thought no harm would come from > using those pins. > > > On Tuesday, March 24, 2015 at 8:05:22 AM UTC-7, Graham wrote: >> >> The Sitara uses a field of pull-up and pull-down resistors to tell it how >> to boot. >> If you put any LOAD on these pins, and your I/O does NOT have to be >> powered, (which would make >> things even worse), you will give it the wrong boot commands, and the BBB >> won't boot. >> >> Go read the section in the System Reference Manual on Boot Configuration, >> and >> the section on Pin Usage Considerations. >> >> >> --- Graham >> >> == >> >> On Tuesday, March 24, 2015 at 9:42:12 AM UTC-5, Khalil Estell wrote: >>> >>> Hello All, >>> >>> I have become stumped by this issue. I am trying to boot up a BBB when >>> connected to the inputs of six MD10C motor controllers >>> <http://www.robotshop.com/media/files/pdf/user-manual-md10c-v2.pdf>. >>> For the most part, it works fine if the BBB has been boot up before >>> *connecting* the direction and pwm pins to the beagle bone black. If I >>> attempt to power the BBB with them connected, the power light indicator >>> will come on, but the status lights will not. The configuration of the >>> circuit is this: I have a custom shield that I made that breaks out the pwm >>> pins and gpio pins I need for the controller. The controllers are powered >>> by an 24V battery power supply rated at 15A output. The BBB is powered by >>> 5V regulator rated at 6A. >>> >>> Here is what I have attempted thus far: >>> >>> >>> 1. Turn on battery, which is powers the 5V regulator and the motor >>> controllers, which turns everything on at the "same" time. BBB does not >>> boot up. >>> 2. Remove cape (with all the connections still on), turn on battery, >>> BBB boots, once the light indicators are no longer all a solid blue, I >>> replace the cape, and everything works, BBB continues to boot up. >>> 3. If I remove all but one input to one controller and power up the >>> battery, BBB sometimes boots. >>> 4. I have attempted to add 1k and 10k resistors between the >>> connections which allowed the BBB sometimes to boot with two motors >>> inputs >>> connected. >>> 5. *Wierd one:* I decided to remove the power from two controller >>> (except for ground), and connect them to the BBB. Still it did not boot. >>> The motor controllers did not get powered at all! >>> 6. *Wierder one: I removed all of the power wires from from both >>> controllers and still the BBB will not boot up if connected to the motor >>> controller inputs.* >>> >>> Does anyone have idea what is happening here? One of my solutions was to >>> use a relay to turn on the power to the motor controllers after the BBB has >>> fully booted up or add a second switch that turns on the motor controllers >>> after the BBB has fully booted, but that plan can not work if merely >>> pluggin in the inputs causes this problem. >>> >>> I do know about this issue: DO NOT APPLY VOLTAGE TO ANY I/O PIN WHEN >>> POWER IS NOT SUPPLIED TO THE BOARD. IT WILL DAMAGE THE PROCESSOR AND VOID >>> THE WARRANTY. NO PINS ARE TO BE DRIVEN UNTIL AFTER THE SYS_RESET LINE GOES >>> HIGH. But in this case, there is no power coming from the input pins. >>> >>> *Last note: I measured the resistance from the dir pin and the pwm pin >>> to ground and they come up 16k and 20k respectively. * >>> >>> I appreciate any suggestions or help on this matter. >>> >> -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- Gerald [email protected] http://beagleboard.org/ http://circuitco.com/support/ -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
