I am using the ATtiny861a and have made it so that the SPI connects to a Radio and an external memory source VIA two different chip select pins but sharing the same MISO/MOSI/CLK line.
Correct me if I am wrong, but are there two different ways that I could wire ISP programming into the circuit? The first way being that I need to put a resistor in each MISO/MOSI/CS/SCK line before the 'Slave' and the other way is that I put a Pull-up/Pull-down resistor into the CS lines. I found this on another site. ( http://www.societyofrobots.com/robotforum/index.php?action=dlattach;topic=10394.0;attach=4420;image )
Which way of programming the circuit would be better(more energy efficient during non-programming/easier installation)? The circuit will be a wireless node so it will not be "functioning" when we are programming it.
(from the link above) If I am using 1.8V to power my circuit, would I change the pull-up resistors to be connected to 1.8V? Is there any downside(more power consumption) to use Pull-up versus Pull-down? Are Pull-up/Pull-down resistors interchangeable or can they only be attached to certain pins? If power consumption is important, what resistor values should I use?