dubnet

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  1. I forgot to mention that the MCU has an internal temp sensor that you could potentially use as part of your design. Mux resistance is listed at 1K (page 32 of the datasheet). If your source impedance gets too high then you run the risk of more noise. If you find your A/D results bouncing around significantly then you may need to drop from 100K to perhaps 50k or less.
  2. If you use the 2553 on your own PCB you will want to replicate the reset circuit (capacitor and resistor) that the Launchpad uses. Otherwise the MCU won't run. On the temperature sensor(s) I was envisioning using something like an LM34 or LM35 placed near the area in the PC enclosure you are interested in keeping cool. If this is done then when the PC is idling along the fans should run slower and when you are pushing it the fans will run at near maximum speeds. I would guess that you have some free four pin power plugs (with 5V) in the chassis. If you add a 3.3V linear regulator to your PCB to drop the 5V then it would resolve your power issue without splicing.
  3. First of all, welcome to the forum! In terms of pin usage you will want to pay attention to pins already used by the Launchpad (e.g.switches and LEDs) to avoid conflicts. With regard to the fan speed control, why not use temp sensor(s) in lieu of the potentiometers fed into the A./D converter? Perhaps just one, or possibly two, would be enough to adequately control the speed of all four fans. Just a thought....
  4. First of all, welcome to the forum! The product you are working with uses an 8052 as it's MCU. This forum primarily deals with the TI MSP43x, TM4C and some of the other general purpose TI MCUs. There may very well be people on the forum with some experience with this chip. However, to increase your odds of an answer you may want to post on the TI E2E forum as well. The following link goes directly to the forum for this product. https://e2e.ti.com/support/interface/usb/
  5. Depending on the length of wire between the master and slave you may need to decrease the pull-ups to about 4.7K or so. Also, your master is sending 4 characters and 1 byte continuously and your slave is looking for those in order. However, you have no synchronization to ensure that the slave is seeing the beginning of a transmission rather than something in the middle. For troubleshooting purposes you may want to simplify the data transmission to just bytes to eliminate that possibility. If you can borrow a logic analyzer (e.g. Saleae) that can go a long way in figuring out what is actually happening on the I2C bus. EDIT: You may also want to try sending some test messages in your code (unrelated to your I2C print routine) via serial.print to ensure that the problem isn't between the slave and the PC.
  6. You can post your code directly into your post by first selecting the "More Reply Options" button at the lower right hand corner of the post reply window. Then click on the icon represented by the less than / greater than symbols < > A window will then pop up that you can paste your code into. It will take care of the formatting (indenting, etc) so the code is readable.
  7. @@Neetee Some suggestions for you so that you can better be helped by the users on the forum: Provide the Launchpad you are using, as well as any Boosterpacks. Provide your code - it is difficult to understand what is happening without this. Explain what is working and what isn't working. And if something isn't working, what exactly is happening and what you have already tried in an attempt to get it working. If you are using any of your own circuits besides the basic Launchpad, please detail that with a schematic. If possible provide a photo of your setup. Sometimes issues have been spotted with this additional information. The upside for you is that you will get more useful information in a shorter time frame. EDIT: Apparently @@chicken posted while I was composing this post.
  8. @energia Thanks for providing the detail on low power modes in EMT. I have managed to pick up pieces of information on LPM here and there but didn't feel I had all the pieces of the puzzle. I did forget to mention to the OP about shutting down peripherals before going into power down mode. A little while back I did some quick experiments using EMT power down modes and Energy Trace. Wasn't able to get data sheet numbers but it was pretty close. Impressive.
  9. My understanding is that Delay() is functionally equivalent to Sleep() in EMT which I believe is LPM3. I also am of the understanding that the Suspend command puts the MCU in LPM4 and requires a interrupt to return to an active state. I welcome those more knowledgeable to correct this if I am mistaken.
  10. You may want to try adding a small delay to your loop as @@Fmilburn did in his example. I have found it necessary to add delay loops in my code as well when dealing with slow (9600 baud) serial. Sometimes just blinking a "character received" LED inside the loop will accomplish the same thing.
  11. Welcome to the forum!
  12. First of all, welcome to the forum! Sometimes doing things in the analog domain can be a viable option. Your requirements said "peak detector" to me when I read them. See the links below for some info on peak detectors and you may be able to find integrated solutions from the likes of TI, Analog Devices, Maxim, LTC, etc. http://www.planetanalog.com/author.asp?section_id=396&doc_id=562072 http://electronics.stackexchange.com/questions/57866/how-to-sample-and-hold-on-very-narrow-pulse
  13. Welcome to the forum!
  14. First of all, welcome to the forum. You may find better success with your question if you start a new post rather than adding to a post that is 9 months old. As to your question you may want to try searching this site for previous posts on implementing a frequency counter. If you can't find what you are looking for then please start a new post and I am sure that someone will be able to help you out.
  15. My guess is that it would only apply to the pin when configured as digital I/O. Given these aren't likely laser trimmed resistors with low temperature coefficients, they would likely add error to the A/D result. Just an educated guess. Perhaps someone more knowledgeable can jump in to confirm.