How to connect ISP header with SPI?

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I'm designing a circuit using the AVR's SPI, and also want to connect a 6-pin header for in system programming, which also uses the SPI ports. I've been unable to find anything about how I should connect the header, without affecting the normal operation of the SPI when not being programmed. Can anyone help?

Thanks

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Check application note AVR042

Stealing Proteus doesn't make you an engineer.

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thanks, what resistor values should be used on the SPI lines? The note doesnt give values

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Because they can't. You have to calculate / estimate the values depending on what you have connected to SPI.

Stealing Proteus doesn't make you an engineer.

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Hmmm, I don't think I've ever added resistors to the SPI/ISP lines and I have many apps with SPI devices.

Use one of those resistors, a high-value one, to pull the chip select of the SPI device to the de-selected condition. Repeat for each SPI device.

For ISP purposes, SPI devices are "easy".

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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How do I calculate them? I'm interfacing with a radio module, what should I look for on the datasheet in order to calculate them?