Stewart, I have samples of the 5 volt version of the 2 and 4 Megabit parts by ATMEL. I looked at several parts before deciding on these particular parts and this particular manufacturer. I chose these mostly because they would be easy to interface (They are serial devices), because I could get them in the package and voltage I wanted, they had the capacity I needed, past experience with ATMEL parts, and last but not least, cost. Even in quantities of 1 or 2 pieces, they are only about 3 or 4 dollars each. This is acceptable to me. The power consumption in my application is only of moderate concern, so I can't give much advice in that area. Also, with these parts you can write to the buffer until it id full, and then send a command to write this buffer full of data to main FLASH memory. After issuance of this write command, the operation is invisible to the user. In the meantime, you can write to the second buffer while the write of the first buffer is going on in the background. This allows you to continue datalogging without missing any data. Once this second buffer gets full, you can write it to main FLASH, and go back to using the first buffer again. Another point of interest to me is that the page size of these memories is 264 bytes. These 8 extra bytes can be used to store checksum data or other information you may want to include. I think from a cost/performance/feature point of view, these parts are hard to beat. But, only you can decide if they do or do not meet the specifications you have set forth as being important in your application. I hope this helps you. If nothing else, I hope to have given you some points to think about. If you need any more info on these parts, let me know and if I can, I'll help in whatever way I can. Regards and good luck, Jim -----Original Message----- From: Stewart Greenhill <greenhil@CENTRAL.MURDOCH.EDU.AU> To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU> Date: Thursday, May 27, 1999 8:46 PM Subject: Interfacing PICs to large (8 megabit) FLASH memories >Hi Folks, > >I'm new to the PIC list and am back into PIC development mode after an absence >of a few years. > >I'm working on a data logging application using a PIC16F84. I need a >low-power design with a large memory. These loggers may be recording for >several years under battery power before being interrogated. > >Currently, I'm looking at a couple of 8 megabit serial flash memory >devices: the NexFlash NX25F080A and the ATMEL AT45DB081. Both operate at >2.7 volts, have a 4-wire serial interface and dual SRAM sector buffers >on-chip. This is important because it allows sectors to be assembled >on-chip before being programmed into FLASH. This style of memory requires >an entire sector to be written at once, and there is not enough RAM in a >PIC to hold the data. > >The ATMEL part looks a little more flexible, since both sector buffers can >be programmed directly to FLASH. The NexFlash part has separate PROGRAM and >SRAM buffers; although data can be copied between the two, only the PROGRAM >buffer can be written to FLASH. However, the decider for me is the power >consumption. At 2 uA standby, the ATMEL part requires twice the power of >the NexFlash part (1 uA). > >Does anyone have any experience (positive or negative) with either of these >parts? Are there any other devices that I should consider using? > >Thanks, >- Stewart Greenhill