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pzw

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Everything posted by pzw

  1. @chwe In the schematics it was not clear if there is a termination circuit inside the CPU... The headache referred to the required implementation of a termination circuit in my design.
  2. Great news! Thanks @guidol. Saves me a headache.. haha .. I suspected that the termination might be in the h2+ ... Thanks for confirming this..
  3. Thanks @guidol! Last question. Was that powered up?
  4. No termination there...??
  5. @chwe the snippets in my post come from their diagram of the module... I noticed forgot to add the snippets from the shield.. I'll add it when I'm home again. But that will show no termination circuit...
  6. I have one more question, which I hope @guidol can help with too... If I read the datasheet of "magjacks" made by Pulse (that is a connector with built in transformers / magnetics) I see the following; There is clearly an set of resistors terminating the lines from the magjack to the PHY (in the H2+)... However on the diagrams there is nothing like this; So I hope that someone can measure for me the resistance between pin 13&14 on the headers of the DUO when it is not plugged into a shield. If there is a resistance of about 100ohms, it means that these resistors are built into the CPU... If not, then I need to add them. (And FriendlyArm might need to revise their shield or module ;-) ) Thanks in advance!
  7. Great! That's all the information I was looking for! Thanks a lot @guidol
  8. I'm currently designing a PCB which will use a nanopi duo board. Unfortunately it is not in stock at the moment so I can't order one yet to verify some measurements. Can someone (@guidol or @larry bank maybe?) who has one sitting on their desk please give me the following info; - Distance between headers. Total width is 1" so I guessed 0.9"... Is this correct? - length of the pin headers. So I know how high it will sit on the PCB - total height of the pins + PCB - is there anything on the bottom PCB which is higher than the plastic on the pin headers? In other words; can I push the whole module all the way down to a PCB and then only have the thickness of the plastic of the pin headers? Or is something "sticking" out.. - How much does the heatsink add to the total thickness? (Or what is the thickness of the heatsink...) Thanks in advance for your help and time.
  9. I don't think aplay supports MP3. Use mpg123 for that..
  10. Which header are you connecting to? Single row or double row? You need to connect between pin 7 or pin 8 and pin 2 on the single row header...
  11. Shorting the power line to ground through a (relative) high resistance flat cable... Check if there are no strands touching at the end of the flatcable (at the connector)
  12. Thanks for the script... I had to adapt it a little, since the script assumes there is a module installed with EEPROM... My question is why...? I have a module without EEPROM ( https://www.aliexpress.com/item/New-I2C-RTC-DS1307-High-Precision-RTC-Module-Real-Time-Clock-Module-for-Raspberry-Pi/32610072259.html ) and had to change line 95 into " if [ TRUE ]; then " , since the original line doesn't work for boards without EEPROM. (It tries to evaluate "--" as a number...) Maybe you want to adapt the script in such a way that it is not depending on the presence of the EEPROM... :-)
  13. Typo from my end, it's indeed 472.. let's blame the human using a phone to type! Haha As far as I know the lower the pull ups, the higher the current, the faster the (parasitic) capacitance of the bus is charged. This should allow higher data rates. Or am I mistaken here?
  14. Those 473 (4k7) resistors are the pull ups. They are very high for a 3.3v application.
  15. @Larry Bank There is for me not a specific reason not to want to use HDMI... The big "problem" I have with the HDMI connection is the size of the connector... I don't want to have a connector stick out on the side since I want to be able to build in the display in an enclosure not much larger than the display itself. For me another option would be a display directly connected a MIPI-DSI port... But my oranges don't have it, and I do not want to use a RPi... The application itself is very lightweight, so the sacrificial OPi would actually be the complete controller :-) ..
  16. Refresh rate of 5 - 10 fps is enough for my application, as long as the update of the display seems seamless... :-) The only reason for the refresh is to make the display not feel sluggish to touch...
  17. All, I am looking for a 7 - 10" TFT display with SPI connection, and with touchscreen preferably via I2C, for a project of mine. I want to use the display to show just a static HTML page, without any window manager etc. Pretty basic principle I think. Looking at the website of www.buydisplay.com I see a few options with regards to the controllers used. The main options are: - RA8875 - RA8876 - SSD1963 I can find online references to the RA8875 being supported by fbtft, but there is also a statement on the github page of fbtft that there will be no more development of fbtft ... Before pulling the trigger on a display, I would really appreciate feedback which controller is supported by fbtft/armbian... :-) Thanks for your time.. Paul
  18. Wrong connection of the panel flat cable?
  19. I guess that means the display is faulty... ?
  20. What happens when you connect the display to a pc? Or maybe a DVD player...?
  21. Which display (link / photo?) and how did you connect it? HDMI? SPI?
  22. I guess this is the best thread for my question; Would it be possible to create a sub forum where "generic" electronics questions can be discussed? A lot of questions are posted in the forum / thread of the SBC in use, while in general most questions & answers are applicable to most (if not all) SBCs...
  23. Forgot to mention; easy way to generate pwm is to use a pca9685 chip connected to i2c. Adafruit sells a board with it, and it even has the right resistors installed so you can hook up a led directly...
  24. Since LEDs are current devices, they cannot be easily controlled in the voltage domain. So if you do not want to do pwm control, then you need to do current control. PWM control is a lot easier! You need to use a driver circuit to control your LEDs. That can be as simple as a uln2803 chip, or a complicated current limiting discrete circuit. First figure out what the voltage is you need to control, and the total amount of current. Then we might be able to help.
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