I am considering a simple, low cost logging dongle for use in harsh environments:
HW
- Cygnal C8051F320 uProc with UART
- Marcell recommends AT91SAM7A3
- RS-232 transceiver (RS-232 level shifter, max232)
- DSUB9 Serial connector
- USB connector
- Vreg (Sot23)
- 1Mbyte SPI flash Sflash (or MMC)
- Marcell recommends MMC. In an epoxy-potted case it can be soldered without a socket. '''I only saw retail prices for larger MMCs. The 1M byte Sflash was melf or Sso8 package and $5 in 100 piece quantities and thus my interest. MMC/SD wholesale price starts from $8..$10 (64..128 Mbyte) and 256 Mbyte is just slightly above $20. The bigger memory worths the cost
- 320 ?
- There will be a few caps thrown in for the level shifter and regulator.
Software
- Identify VEMS when attached and issue data dump requests - log resulting data stream
- Accepts commands when connected to host (PC or PDA) to dump data
- On board USB rechargable coin cell or host powered (5V on VEMS DB9 or USB on PC/PDA)
Conclusion
BOM, board, assembly and testing = cheap
Firmware = easy
Podded in epoxy = ruggedness
Anyone interested, please chime in. Cost for members should be kept in the $20 range.
Notes
- The group effort has (long-pending) plans on the following:
- firmware support for v3.x MMC logging GenBoard/LoggerIntegration is a bit confusing. See GenBoard/LoggerIntegration/MMC
- arm-boost is the codename of the low-cost (no fancy connectors) potted board (under development; 90 ARM uC-s are ordered for it and come in 2006 March) that is mostly sensing / networking / logging (but very restricted when it comes to power outputs). Useful for surprisingly many applications, logging is one. I suggest you join the development - first the MMC firmware _code_ than this.
- It's possible to roll an even smaller board (than arm-boost, perhaps with a different uC to save another $1 with only $900 of development task) but probably only justified if >500 can be sold.
Bill's choice
- currently no C skills and do not have the tools to contribute to the above (schematic or layout).
- Note that anyone who programs assembly, C is very easy and fun, and a good investment (takes little time anyway). The tools are easy to install (eg. winavr is just a 1-click installer)
- I can do schematics and layout in Orcad in my sleep (I am not good, it is just too easy).
- It is less time for me to generate it in assembler and Orcad.
- uC: my path will use Cygnal C8051F320 as I have the tools, can code the 8051 assembler, it has UART and USB on board as well as all the clock stuff.
- No need for others to support software or hardware design.
- If interested, it can be for the group only as a development tool.
- There is no need to produce it (or have it meet production criteria). Bill will probably have to do this anyway for my work.
- PCB+PNP production is actually not that hard/costly given that we'll have several PNP-d 2-layer boards soon to merge with (doing the PCB+PNP together saves costs).