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how to connect the ISP to the ATmega48

OK, largely based on advice received in this group, I'm now trying to use a naked ATmega48 (28-pin DIP) as my controller rather than buying some fancy controller board. :)

I received the chip yesterday, along with a shiney new AVR-ISP mkII programmer. Now... how do I get these together?

I thought there would be documentation included showing which pins of the microcontroller should be connected to which of the six pins of the female connector on the ISP. But, to make a long story short, I can't find any such documentation. Can someone spare a clue?

Thanks,

- Joe

Reply to
Joe Strout
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Never mind, some helpful folks on the avr-chat mailing list, plus some more creative Googling, eventually turned up the documentation I needed. I'm still amazed that Atmel didn't think it important to include the ISP user's guide with the device, since they were including a CD anyway... but I'm starting to think that the documentation is kept intentionally hidden to keep away the unfaithful. :)

Best,

- Joe

Reply to
Joe Strout

Atmel has a good line of microcontrollers, and the free tools do everything necessary and are well integrated, but finding all the information necessary to make everything play together is excessively difficult.

I'm currently struggling with a situation where AVR Studio's programming feature can talk to a board via the JTAG port, but the debugging system can't connect properly. See

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It's probably some configuration issue, something involving installation options, or something else dumb like that, but I haven't been able to make it work yet.

John Nagle

Reply to
John Nagle

Found out what was wrong. Low power supply voltage. The board I'm using needs 12VDC or 9VAC before the +5 supply comes up properly. (Yes, that's wierd, but look at the schematic. Note the zener diode in the power circuitry at the upper left. They wanted

12VDC for the Dallas 1-wire interface, and get 5 VDC from that. So they put a 3.3V zener diode in to drop the voltage before the 78L05 regulator.)

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With only 9VDC in, the processor comes up, but the +5 supply is around 4.5V. The AVR will happily work at that voltage. But the ZM33064 reset controller senses it as a power fail and holds the processor in reset. In that state, it can be programmed, and talked to over the JTAG port, but any JTAG function that requires bus traffic fails. Hence the wierd "programs but won't debug" symptoms.

John Nagle

Reply to
John Nagle

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