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Adding more SPI to MONOCHRON
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Adding more SPI to MONOCHRON

by Squar0L on Sun Feb 28, 2010 2:13 am

The design guide says "LCD_CS1 is always the invertion of LCD_CS0". I'd like to pack one mode SPI device on that bus - can the Designer confirm a HCT139 or so is doable to better use that two pins?
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Re: Adding more SPI to MONOCHRON

by Squar0L on Sun Feb 28, 2010 12:51 pm

OK, I was confused on the roles of KS0108 pins hooking up to SPI of the MCU. It's clear now the display has nothing to do with SPI. I think I can hook up a new SPI device to MISO/MOSI/SCK and drive the CS from the freed up chip select of KS0108. How do port C and D pins behave on the AVR when it's in ISP programming mode? Float?
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Re: Adding more SPI to MONOCHRON

by adafruit on Mon Mar 01, 2010 3:37 am

when the chip is being programmed, the pins are being used. just make sure the CS line is pulled down by default (or whatever) so that the SPI device doesnt try to bash the programming pins.

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Please be positive and constructive with your questions and comments.