Author Topic: is my pocket AVR (usbTiny) fried?  (Read 1094 times)

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Offline Dan MoosTopic starter

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is my pocket AVR (usbTiny) fried?
« on: June 25, 2016, 07:57:17 pm »
My pocket AVR programmer (its a usbTiny clone from Spark Fun) will not let the reset pin on the target go high when its not programing. It was fine before. Removing the wire from the programmer to the target's reset pin allows it to go high.

I get half a volt on  pin 16 of the prgrammer's MCU (the pin that feeds the target reset).
I get half a volt on the corresponding output from the buffer between the MCU and the wire heading to the target reset pin. To me that sounds like the buffer is doing its job.
I get 5 volts from pin 8 on the programmer's MCU, which is labled CTL on the schem, and heads to the same buffer's inverting(?) input. Not sure how this buffer works, so sorry if I'm being confusing.

I get proper voltages on power pins of MCU and buffer chips

MCU crystal pins have a 1vPP 12mhz pulse on them, as I believe they should.

There are LEDs corresponding to the D+ and D- lines from the USB jack. D- is constantly lit, D+ flickers when I attempt to use the programmer. D- being lit constantly seems strange to me. It doesn't flicker when I try to program.

There are two status lights, stat1 and stat2. Stat1 is always lit, stat2 flickers when I attempt to program. My belief is that this is normal.

I get an RC=1 error from avrdude when I try to program. I've tried a couple different projects that before programmed fine with the same programmer, and they now cause the RC=1 error. I'm pretty sure that my hookups are good.

Again, the only obvious problem is that the target's reset pin is held low, even when not programming. I think that alone would be enough to cause the avrdude error.

So, what else can I check? Is mt programmer fried?
 


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