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Errata of BeagleBoard

Thứ Hai, 20 tháng 6, 2011 / 09:16

  1. Boards revision A only: The DC power jack pinout is incorrect on the PCB layout. DC_5V and GND are switched on PCB layout. Normally, the power jack has DC_5V on the center pin and GND on the sleeve (see Figure 20 of Beagle HW manual). But on revision Ax boards the PCB layout has GND on center and DC_5V on sleeve. For this reason it is currently removed. It will be back on the Rev B board. Workaround is to remove wire connecting the two power pins on revision Ax boards and use external power supply with switched connector (do not connect anything to the “?” terminal. USB power will be permanently disabled and the board can only be powered from the 5V.) See Koen's Beagleboard powermod picture with short descriptions, too.
  2. Boards revision < A5 only: There is excess voltage drop across R6 which is used to measure the current consumption on the board. This needs to be a .1 ohm instead of a 1 ohm resistor (SMD 0805). All revision A5 boards have been updated to .1. You can also just solder in a jumper to J2 bypassing the current read point. This issue can cause issues with the USB host port as the voltage supplied to that port can be too low.
  3. Boards revision A only: User LEDs 0 and 1 are shorted on the layout preventing them from being controlled individually. You need to control both GPIO_149 and GPIO_150 to turn on or off both LEDs. This is fixed in the Rev B boards.
  4. Boards revision < A5 only: There is an issue where on some boards the 1.8V has excessive noise on it. This is the result of two incorrect parts L1 and L3 being installed on the board. The inductors that were initially installed in the switchers are 100uH and need to be 1uH. This change will require that the board be returned for update. To check for correct parts, have a look to bottom of BeagleBoard. L1 - L3 are the larger parts there. They all have to be labeled with "102" (== 1uH). If any of these three inductors are labeled with "104" (== 100uH) they are wrong and have to be exchanged.
  5. Boards revision A and B: USB HOST (EHCI) failures. See issue 15 and USB host test reproduce. This is a hardware defect. Most probably Rev. B board does not have the EHCI USB connector mounted. Workaround: Use OTG port with something like mini A to USB A adapter instead.
  6. Boards revision A and < B4: Plugging in a USB OTG cable will prevent Beagle from booting (with git kernel), see issue #19, too. This is due to missing filtering capacitor at USB OTG VBUS. When the kernel driver detects that a USB OTG cable is inserted it enables the charge pump to generate VBUS. With no filtering VBUS looks like any switching regulator output with no filtering -- a huge voltage spike when the switch is on, followed by a rapid decay to a low voltage until the next switch on period. The capacitor is there to store energy between the output switch ON and OFF time, the feedback loop in the regulator does sample the cap voltage. Fix is to piggy-back solder a 0603 2.2uF ceramic capacitor to D3, see VBUS modification D3 picture. Revision B4 boards and newer have this fix applied. Thanks to Steve for debugging this!
  7. Boards revision A and < B5: There is some issue with 32kHz clock depending on system configuration used to clock some OMAP3 peripherals. From this e.g. GPIOs, GPTIMERs, and USB on Beagle might be affected. See Issue 22. Symptom from this is that after booting Linux kernel serial console hangs after some time and no serial input/output is possible any more. There is one software workaround and one hardware fix for this: (A) Software workaround: Don't use 32kHz timer to clock Linux, instead use MPU timer. (B) Hardware workaround: Remove capacitor C70, which improves the 32kHz clock quality and avoids hang-up. Note: Revision A boards have capacitor C70 at the same location as rev. B boards. Note: Board revision >= B5 removes capacitor C70.
  8. Random boards, quite rare, revision < B6: Some random boards and quite rare, show directly after purchasing broken serial communication from host PC to BeagleBoard. Symptom is that you get a new board, get serial output from BeagleBoard in terminal program, but can't type anything at U-Boot prompt (Note: Don't mix this with errata #7. With errata #7 you are able to use U-Boot normally, but Linux prompt input stops after some time). Most users don't have this issue, though. So, first double check your serial configuration (FAQ1, FAQ2 and FAQ3). Only if you are really, really sure that anything with your serial connection is fine, consider sending the board back doing a RMA request. This issue was resolved on revision B6 and later boards.
For additional (software) issues and enhancement requests see Beagle board open point list & issue tracker, too.
Note: BeagleBoard revision B6 uses different package for U9/U11.

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