I2C, SPI & FRAM problem

[steve382]

Hello. I have an Arduino Uno R3 fastened to my breadboard to interface circuits to the computer with. I had developed circuits useing MCP23008 bus expanders that were working well. An I2C scanner program reported their addresses at 0x20 thru 0x27 for chip addresses 0 thru 7 and two unknown devices at 0x00 and 0x70. I then tested the 64K FRAM breakout board and it worked well also. When two bus expanders were reconnected they could no longer be accessed. The I2C scanner reports their addresses at 0x26 and 0x27 for addresses 0 and 1. The unknown devices are no longer there. I cannot access the expanders at their new addresses nor get them working again. The I2C bus is connected to digital pins 16 SDA and 17 SCL. The FRAM is connected to digital pins 10 thru 13.

I removed the FRAM,its programming files and the SPI.h. The problem remains. A irreversable change has occured to the Arduino. I would like to add the FRAM to my robotics project which has expanders, ADC and PWM boards connected to the digital pins 16 & 17 but I now wonder if it would cause a similar change to its Arduino.

I checked the library files you offer for the MCP23008. They say they do not support the interrupt functions of the chip. My project needs that. I have downloaded the library and am hoping to hack it until it works for interrupts. Will all I2C devices have to be connected to Analog pins 4 & 5 if useing the SPI FRAM?

Please explain what has happened. What are(were) the unknown devices? Is this change reversable?

Thanks,
Steve

[Franklin97355]

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