This is my first message to this group. I have been working with the AVR for the past two years. I have used the AVR for various control applications.
I am working on a project to interface an AT45DB081 (data flash) to an 8515. The data flash is device which has a max Vcc rating of 3.5V. I am unable to find an 8515-4 which operates at lower voltages here in India. The data flash is an SPI device. I would like to know how to interface the 5V AVR to the 3V data flash.
I have also had a lot of trouble connecting more than one device on the SPI bus with AVRs on the bus. One problem is that the slave devices get powered up through the SPI pins even when their Vcc are physically disconnected. Does anyone know why this happens? This is a problem especially at power-up when I want some slaves (such as the Vector 2x module from Precession Navigation) to power up after the master is completely initialized.
Another problem is also that I have data corruption problems when more than two devices are on the same bus. E.g. I have a board with 2 AVRs (a 4434 and 8515) and a maxim MAX3100 (a UART) on the SPI. Data almost always gets corrupted when I transfer data between these three chips. The 4434 is the master and the other two are slaves.
Waiting to hear from u…
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