RESn problem
Mart1970
Posts: 23
Hello
I have a problem with the RESn .
I made a proto board with the dip version off the propellor.
When i measure the port, i measure 0 vdc.
Now I build a new proto with the lqfp version off the propellor.
And now I measure 3.3vdc on the resn port.
And i can,t program the chip.
What is going wrong?
Is the chip broken?
Or do I have to use a pulldown resistor.
Hope someone can help me with it.
I have a problem with the RESn .
I made a proto board with the dip version off the propellor.
When i measure the port, i measure 0 vdc.
Now I build a new proto with the lqfp version off the propellor.
And now I measure 3.3vdc on the resn port.
And i can,t program the chip.
What is going wrong?
Is the chip broken?
Or do I have to use a pulldown resistor.
Hope someone can help me with it.
Comments
If your BOE pin is tied low as is normal then the only way that RESn will be low itself is if the supply voltage has dropped too low. Just check the supply with a meter but also take note that if there is ripple on the supply then the meter won't normally show it. Use the AC range to check for ripple which shouldn't be more than tens of millivolts maybe.
General tip for troubleshooting is never make any assumptions, check everything if you have to and be methodical, tick the boxes and cross check the cross check. This will greatly help you to keep your head of hair and learn to tackle problems.
btw, I think you meant pullup resistor but no, you don't really need one although a 10k or so might be used especially if the signal is running off board. Also ground all the Vss pins and tie all the Vdd pins to 3.3V, failure to do so may result in damage to the chip or erratic operation at least.
I get 0 vdc at RESn.
With the lqfp version I did the seem
and I get 3.3 vdc, at RESn.
Not what I asked and that is exactly the same as you originally stated. You need to read the reply and follow through and get some results that add to what you and I already know. Remember, no assumptions.
and all the vss pins to vss.
also i have tested the power supply I get a very nice flat 3.3 vdc.
What i don't understand is
You say that the only way the RESn is going to 0 there have to be under voltage.
But why can,t i program the lqfp version.
And the dip version is programming perfectly (with 0 vdc at RESn)
Sorry, not enough information. I could present a problem and test everyone's mettle by holding back on information and let them effectively keep guessing. You are the one that is holding back though because you have not confirmed that all your Vss and Vdd pins are connected correctly which btw a photo could speak a dozen replies. If you needed to get it to work because you were trying to win a big cash prize then I am certain as are you that you would be trying a whole lot more and feeding a lot more information to us. Think of it like this then if it helps so that you are not repeating yourself when you could be telling us other stuff where we might go "aha, that's your problem right there".
What you report is exactly the opposite of what I would expect. Normally RESn would be high, and a low external pulse initiates the programming process. How is your chip programmed, for example, using a USB circuit? Can you supply a schematic or a reference to the circuit you are using? A photo or Gerber of you your SMT board might help too.