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ut-ras / RASBooster2013

Design of simple booster board for the LM4F Stellaris Launchpad. Compatible with RASWare2013
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4 unnecessary resistors #3

Open robz opened 10 years ago

robz commented 10 years ago

For whatever reason we decided that the 4 resistors in the middle-ish of the boosterpack should be removed. So, there probably shouldn't be holes for them at all.

theotherjimmy commented 10 years ago

In a perfect world, we would have another resistor for each motor; making a total of two resistors per motor: one pull up and one pull down. This would put any motors in brake mode if they were not configured. I think this is why we had originally put the pull downs on the booster. However, this complicates the hardware, and I don't think auto-braking is worth the added complexity.

geky commented 10 years ago

@theotherjimmy, Actually the motor drivers have built in pull-up/pull-down for that exact intention.

theotherjimmy commented 10 years ago

While I would love to have internal pull up/downs, My reading of the data sheet only indicated internal pull up/downs on the outputs for open circuit detection. They are mentioned on page 6 of http://www.infineon.com/dgdl/tle5205-2.pdf?folderId=db3a304412b407950112b4381da46a3c&fileId=db3a304412b407950112b4381e296a3d . I hope I'm missing something.

geky commented 10 years ago

You are quite right Jimmy. I'm not sure how I missed that.

geky commented 10 years ago

@theotherjimmy, that is a bit concerning. I contributed the pull-ups that are connecting the wrong way as the reason behind an issue in which the motors were not driven correctly. I thought they were having competing against the internal pull-ups and causing issues.

When the resistors are removed, these motor drivers function correctly. Do you know of any reason the resistors could be causing an issue? Has anyone had tested a breadboarded motor driver with the correct pull-up?