Re: [Usbpicprog-technical] PIC16F84A support

[Frans S. <fra...@gm...>]

Hi Francesco,

Francesco Montorsi wrote:
> Hi,
>
> Frans Schreuder ha scritto:
>   
>> I don't think it should be very different, do you have the latest firmware?
>>     
> I should have the firmware 0.1.1; I'll see what happens with the firmware in trunk.
>   
Yes, try that one... It's also compiled, so you can just load the hex 
file...
>
>   
> good idea; I'm currently using a cable 27cm long. I'll try with a shorter one 
> even if the electrical length of the cable at 8Mhz is about
>
>   L = 0.27/37 = 0.0073
>
> which I think could be considered negligible.
>   
In terms of wavelength you are absolutely right, but what about inductance?
If we consider the wire to be 1.5nH per millimeter, you get something 
like 400nH which will result in 20 Ohms reactance at 8MHz. Luckily the 
programmer doesn't run at 8 MHz, but something closer to 1MHz, so this 
wouldn't be a big problem, it's just a couple of ohms.
But you shouldn't make them much longer than that!

Cheers,

Frans