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  1. R

    Voltage threshold issue

    Or are you saying set drive 1 and drive strength to 2mA and it will work i.e. meet requirements for VoH?
  2. R

    Voltage threshold issue

    I have seen that it is configurable as I/O pin. Cbus Drive 1 sets this to a high looking at table 3.7 Do we need to adjust the drive strength to 2mA? I can see all this. But can't see how this works with a internal pull up of 68K and pull down of 10K? Powered from 3.3V. I apologize but can't...
  3. R

    Voltage threshold issue

    Also the internal pull up from cbus3 is 68K. So if we have a 68K with a 10K pull down, vcc is 3.3V, this equates to around 0.5 V we are seeing with the scope. I am not sure how the 2mA for Voh for the gpio pin is configured. I presume via FTPROG utility. But would I then not have to adjust my...
  4. R

    Voltage threshold issue

    The pull down is hardwired with a 10K resistor. We are only using cbus3 to toggle a high level.
  5. R

    Voltage threshold issue

    I have measured the value of the internal pull up. Which is 66K. I think I have found the issue ViL for the STM32 is 0.43V, ViH is 1.26 V (minimum) . We are getting 0.5V on the boot0 pin i.e. indeterminate area. So it could be a logic 1 or 0. The 10K pull up changed to a100K results in units...
  6. R

    Voltage threshold issue

    Thanks for your reply. However, I can't understand how a voltage of 0.5V can he recognised as a logic 1 on the STM32, which has a minimum ViH of 1.26V.
  7. R

    Voltage threshold issue

    Yes sure.
  8. R

    Voltage threshold issue

    Hi all, We are trying to use a FT230x CBUS3 to control the BOOT status of a STM32F215. The boot pin of the STM32 is tied to 0V via a 10K pull down. The internal pull up of the FT device is used to toggle the boot pin. I have attached a diagram. We are seeing a voltage of 0.5V which does not...
  9. R

    Usb 2.0 component selection

    Thanks for sending the URL. Regarding the impedance, is this going to be a resistive loss at 100MHz. I am sorry but not sure. Can you help?
  10. R

    Usb 2.0 component selection

    Thanks for the reply. I can't see to open the link you sent for the discussion on the 1/10 wavelength. Also if my cable had a impedance of 50 ohms, then would the voltage divider not be 600/(600+50) x 5V = 4.6V? If the voltage divider affect is very low would that not prevent the circuit from...
  11. R

    Usb 2.0 component selection

    , I am using USB 2.0 full speed for a design. Power to the electronics is 5V from the USB, into a FTDI device ( which has an internal 3V3) regulator to power my electronics. I have a couple of questions, FTDi recommend a LC filter, they have also added an extra 10nF at the input and 4.7uF to...
  12. R

    Reset issue

    The supervisory will be a open drain type. However the FTDI is a GPIO which can be configured as an output or input. Hence my question about using a diode?
  13. R

    Reset issue

    Thanks, I will try using the open collector supervisory first with no diodes as pointed above in your feedback.
  14. R

    Reset issue

    Can I omit the diodes if I use an open drain supervisory device?
  15. R

    Reset issue

    I think based on what you mentioned. This is what I require? Would the forward voltage of the diodes matter, I think they might, are Schottky diodes best for this application?
  16. R

    Reset issue

    Hi, Thanks for your help. I am looking to change the supervisory to open collector with a pull up. Would I still need the both the diodes? If I connect the supervisory output directly to the microcontroller. Then just have one diode on the CBUS0 line. So the reset works under low voltage. Then...
  17. R

    Reset issue

    This is what I have. The supervisory circuit works and resets the micro once it falls below it's threshold level. I can't control using the CBUS0 line. I thought because the output of the supervisory is tied to VDD, hence trying to pull it low won't work. I am thinking of using an open collector...
  18. R

    Reset issue

    Hi, Yes I agree but it doesn't. The supervisor works fine i.e. if the voltage falls below the threshold it resets the PIC. However if I try and force the supervisor output (which is connected to the reset line of the PiC) from the CBUS0 of the ftdi device, it stays at 2.5V.. Is it because the...
  19. R

    Reset issue

    Hi all, I am using a ft232r usb UART device. I use cbus0 to control the reset line of a supervisory ic @3v3. The supervisory ic also connects to the reset line of a PIC microcontroller. The supervisory device is active low with a push pull output. It is a device from ON semi CAT809JTBI-GT3. I...
  20. R

    USBC

    Hi all, I am using a USB C connector in a design. This is a receptacle that fits into a PCB. There are 2 x D- and D+ lines. These are connected together as per the guidelines. This is a through-hole connector. I have attached a picture of the layout of the said connections. One set of tracking...
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