However, 32KB was a bit less than I wanted for the Data_Logger function, so I decided to replace the chip with its bigger brother the MB85RS1MT (1Mb = 128KB capacity) - a drop-in chip - OR so I thought.
Actually, mechanically and electrically the two chips are essentially identical - but, I could not read or write to the new chip - so not quite the drop in I had thought. I checked and rechecked the command set, pin compatibility, etc - all to no avail
.To make a long story short - the problem was that the MB85RS1MT - requires a 24 bit address rather than the 16 bit address that worked on the 32KB chip. I know, I know
- the 128KB size of the large chip should have tipped me off immediately that 16 bit address would only work on a 65KB or smaller chip. Another related thing I discovered (at least I think this is correct), it appears the 16 and 32 bit modes of the PIC32MX795F512H SPI module only applies to the Data transmission and it appears (based on the fact I could not get it to work with the FRAM chip) that the "slave" chip must also be capable of data transmission in the same mode. The FRAM chip is limited to byte size data exchange. So I presume the 16,32 bit modes would work with another PIC32 in "Slave" mode, but could not verify that. If I am incorrect in this conclusion, I would appreciate knowing.
Thanks
But, though I would share this with any of you using the Fujitsu FRAM chips.
