iscp not working when external components are onboard

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Hi, 

 

I have connected to attiny85 MISO pin a 680 ohm resistor in serial with NPN transistor base on a personal board

And I cannot read the fuse or program an attiny85 

I use arduino as isp or usbasp to program and have the same problem with both programmers. Attiny85 and arduino ISP are supplied with 5V

 

If I remove the 680 resistance the read of the fuse and flashing is ok

I would not expect that could disturb the flashing, is it normal ? 

 

Thanks,

 

Franck

 

Last Edited: Sat. Jul 9, 2016 - 06:33 PM
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It totally depend of the driver in your programmer! (and VCC are they the same or is there a difference)

But I guess both the LED and programmer would work if you use something like a 2K7 resistor.

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Thanks, but hfe is 40 min in the spec off the S9013 so 2K7 resistor could be a little high to provide 100mA to the led

I will try with a 2k7 resistor as I replaced with  an npn with a higher hfe

 

 

Last Edited: Sat. Jul 9, 2016 - 06:34 PM