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  1. R

    PiC A/D loading signal

    If i try and use a 200K and 100K, woyld that be a sensible thing to do. As i am not using the A/D of the PIC, di i need to worry about input impedance of the I/O line.
  2. R

    PiC A/D loading signal

    The source is a feedback from a piezo at 3KHz. It is 7V pk to pk. Hence the voltage divider to bring it to a level that the PIC input can handle.
  3. R

    PiC A/D loading signal

    Hi I have a voltage divider circuit consisting of a 20K at the top and 10K to ground. Centre pin to PIC A/D. The pic is used to measure high to low transitions of a square wave pulse. So the A/D is not used. I am sure my signal is being loaded. Can i add a voltage follower after the voltage...
  4. R

    Interfacing a NTC thermistor to a PIC

    Hi thanks for your reply. I was looking to at least measure a change on 1C. So think the thermistor and voltage divider will be the best option. Thanks
  5. R

    Interfacing a NTC thermistor to a PIC

    The accuracy i require is thst it must perform as good as a diode. If you apply a constant current to a diode (1n4148) then the temperature can ve neasured by 1C/2mV 1 degree for 2mV. So something like this or better. Thanks
  6. R

    Interfacing a NTC thermistor to a PIC

    Hi I will look at the platinum RTD. I think they are expensive than a thermistor. I was slso thinking of using a diode to measure temperature, which could be cheaper still. Am i correct in saying that R13 and R14 set a voltage at the inverting input. R12 and RTD set an adjustable voltage at non...
  7. R

    Interfacing a NTC thermistor to a PIC

    I have a further couple of questions : If R(25) = 10K at say beta of 4200 for example Then how do i calculate the R(25)/(100) from a typical graph? I know it is the difference between resistance at 25C and 100C but where does beta and constant K fit into all of this? thanks
  8. R

    Interfacing a NTC thermistor to a PIC

    HI all, Thanks for the advice and help. I am looking to measure from -10 to 70C The part that I have selected is NCP series from murata, it is 10K. I was thinking if I use this as a voltage divider with another 10K and feed into a PIC. How can I compensate for lead resistance? I am trying to...
  9. R

    Interfacing a NTC thermistor to a PIC

    Hi I have a NTC thermistor. I want to connect to a PIC (PIC18F4520) A/D for temperature measurements. Is a simple voltage divider circuit good enough? The curve is non linear for the thermistor. Is there anyway of overcoming this in hardware? Or Software. Finally if i use a PTC thermistor are...
  10. R

    Checking PIC18F4520 Timer 0 overflow

    Hi all I have already tried the suggestions that you have mentioned. Clearing the timer0 overflow flag and setting both global and peripheral interrupts. For some reason i get the success LED switch on all the time. I have also tried switching timer0 on by using TMR0ON = 1. I am sure this is...
  11. R

    Checking PIC18F4520 Timer 0 overflow

    Hi I can send it again with more comments. Thanks
  12. R

    Checking PIC18F4520 Timer 0 overflow

    Hi I have attached the code. It is a reaction timer. The start LED lights after 2 seconds. Then you have 200/2.048 seconds to hit the button. If you do then the success LED is lit. I am getting the success LED on all the time. I am using the internal oscillator set to 500KHz. The LED will light...
  13. R

    Checking PIC18F4520 Timer 0 overflow

    Hi Thanks for the reply. I will post the code today. I thought thst i had it cracked by using TMR0L. However it still doesnt work. I will post it later today. Thanks
  14. R

    Checking PIC18F4520 Timer 0 overflow

    Hi I am using MikroC compiler for the PIC18F4520 family. I want to know how I check if TMR0 has overflowed? I have seen on a PIC16xxxx device it is just as TMR0, the following are snippets of code for a PIC16F device :- i.e. TMR0 = 0 /*clear TMR0*/ while (TMR0 < (int) 500/2.048)) How do I...
  15. R

    Start up I/O lines of PIC micro

    Hi Harald Thanks for your reply. I have these LEDs tied to 3V via resistors and the cathide of the LEDs going to the I/O lines. So a logic 0 will light the LED. How can i make these as an input with the LEDs configured as above? Thanks
  16. R

    Start up I/O lines of PIC micro

    Hi all, I am writing some code for the PIC18F4520 micro..some of the code is to flash LEDs dependent upon certain conditions. I have set these I/O lines as outputs. I am noticing that on switch on these LEDs are lit, sometimes randomly. Should i make I/O lines as input initially to avoid this...
  17. R

    Wanted: Electronics components

    Hi all I am after some electronic components so that i can build some circuits. Looking for resistors, capacitors, transistors, FETs, transformers, LEDs etc. Most will be through-hole so i can prototype on breadboard. Other ghan RS components or Farnell I cant seem to find a good resource which...
  18. R

    Serial communications resource for PIC in C

    Hi all I use Mikro C and PIC18F family for my projects. I wanted to ask if there is any good book to teach serial communications with easy to follow examples in C. I am after RS232, RS485, USB, I2C, SPI and one wire examples. The examples need to be easy ti understand and working. Thanks in...
  19. R

    Using text editor within MPLAB v 8.92

    Hi All I have MPLAB v8.92, which i usr to prigran PICs in C. I wanted to ask if there is anyway i can use a different text editor to compile via MPLAB, then recompile in MPLAB or even using another compiler. Is that possible? Thanks in advance.
  20. R

    Programming c on raspberry pi

    Thanks for the information. Even if the compiler defaults to c++, i think i can still use c ? Is that not correct?
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