I am working on a Senior Design project involving the design and construction of a 16 bit data logger. We would like our unit to have 8 input channels, 16 bit resolution, and USB interface (if possible). We would also like all components to be through hole mounted to simplify hand assembly. All measurements taken will be low speed and size of the unit is not a major concern (within reason) Are there any ADCs, microcontrollers or combinations of these that you would recommend? We are focusing on cost and simplicity of design and programming (because we don't have a lot of experience in this area). Thanks for your help, Tim
None of that should be a problem except "through hole mounted" IMHO. Your selection of micros is much wider if you don't insist on through hole mounted for that part. You might consider using an adapter like these http://www.accutekmicro.com/press_details.cfm?Press_ID=18 to simplify construction. I don't have a specific micro recommendation, but a technique you could use for selection. FIND TOOLS FIRST! The greatest micro in the world won't help you at all if you have to use a cranky assembler or flaky compiler. On the other hand, if you have really great tools, rolling your own USB support (rather than having it all in hardware) wouldn't be quite as painful as it might be otherwise. Just MHO. Good luck! Ed
There are so many devices out there. If you went with TI data converters, there are many 16-bit ADCs, some with through-hole pinouts. The surface-mount packages are much cheaper and have better specifications, for instance there are some available with 8 input channels. Parametric table: http://focus.ti.com/docs/search/vpa...param_table&templateId=4&showAssociated=false I suppose you'd want a microcontroller as well. Many of the ADC chips have an serial interface (synchronous) which is simple to connect to most microcontrollers. If you want USB functionality, there are many USB microcontrollers available. Motorola makes some useful ones, good for peripherals and not overkill for a simple data collection system. If you decide to incorporate USB, investigate the HID protocol. They are relatively simple to program for on the embedded device, and you do not need to write an actual driver on the host computer side; simply use readfile commands and get your data. If necessary you could make your device appear to be a keyboard, and when a button is pressed on the device, it would type all of the voltage levels with carriage returns in between; seamless input to an Excel spreadsheet or other application. I did a USB device for my senior project, and it wasn't easy since I too hadn't had much experience. It worked though. Given another chance, I would probably use one of FTDI's USB interface chips instead. They add another device to your board, and you can't claim to have programmed the USB interface, but it would leave a lot more time for correct documentation. What use is a perfectly functional device, if the report doesn't convey that fact?
