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.
