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Using nano clone as an ISP on a breadboard- as shown here - http://www.martyncurrey.com/arduino-nano-as-an-isp-programmer/

Previously, it worked great. However, recently, chips that I have bootloaded and programmed have, when added to the breadboard for reprogramming, caused the USB connection to drop. The heartbeat LED on the nano also dims slightly which makes me wonder if it's a power issue?

Either way, this means that I can't program the chip.

Does anyone know how to fix this? The breadboard circuit will happily program new chips.

The programs on the chips that aren't working often include blink on pin 19 on the DIP chip (D13) - and when I disconnect the link from this to D13 on nano, the USB connection is restored.

But otherwise I am very confused, have got about 7 chips with the same issue and would be great to fix it.

Ideas? Thanks

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  • When you put a chip-to-program on your programming breadboard, are any of that chip's pins connected other than SCK, MISO, MOSI, RESET, VCC, GND, and crystal? – James Waldby - jwpat7 Sep 25 '16 at 2:28
  • Aref and avcc also connected to +5v. But other than that, no. – Calum Nicoll Sep 25 '16 at 9:21
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    After replacing naked wire from D13 nano to SCK on chip with a 330ohm resistor, I was able to program 3/7 of the chips. The others still exhibit the problem of not being recognised. Ideas? – Calum Nicoll Sep 25 '16 at 9:45
  • I don't know what the problem is or why the 330Ω resistor made a difference. If you have a storage scope, verify that Reset is staying pulled low and that SCK transitions are clean. See diagrams and discussion on pp. 2,3 of Atmel's AVR910: In-System Programming document. Note, the resistors in figure 3 there are between the device being programmed and its SPI peripherals, not between the device and the programmer, so are not the same as adding a resistor like you did. Also, have you tried any other values in series, like 100Ω or 1000Ω? – James Waldby - jwpat7 Sep 25 '16 at 23:01

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