Hi Steve, 1) pay attention to what you mean with 1.8V operation: at that voltage, the MCU x1xx and x2xx (I don't know the other families) will _not_ be able to write his own flash at runtime; the minimum voltage for writing it is 2.7V for the older x1xx and 2.2V for the new x2xx. If you only need to read the flash but not writing it, then it's fine.
2) UART comms without any crystal aren't very dependable; the integrated RC oscillator (even in the new x2xx family) has a few percent tolerances, which is usually not enough for reliable standard UART. If you want to keep current consumption at a minimum, you can avoid using the high-frequency quartz, but you have to at least include a watch crystal for the Auxiliary Clock. I had a similar problem and I solved it by periodically calibrating the internal DCO with respect to the watch crystal. Periodically means well within the time that the DCO takes do drift up to the maximum (or minimum) frequency around that of the UART. 2006/4/20, Steve Franks <stevefra...@ieee.org>: > Hi all, > > I'm switching my tooling from AVR to MSP. I'd like to make some CC2420 > ZigBee/MSP modules (think AirBee-light MSP430 demo), and I'm wondering which > MSP variant folks would suggest. > > Design criteria, in order of importance: > > * Small (QFN package) > * 1.8V operation > * SPI (obviously, for CC2420) > * Uart, 38.4k operation w/o crystal preferred > * >4 GPIO's > * I2C > * Adc > > Also, what solution is suggested for flash programming & debug (can be two > items)? Usb prefered, 802.3 ok too? Has MSP standardized on a connector and > pinout for prog/debug? > > Anybody want to buy a couple boards when I do a run? I'm planning a 24-pin > extra-wide (0.9") DIP format so we can stick it into proto boards directly, > and a carrier with some screw-terminals, gpio buffers, some solid-state > relays . > > Thanks for the info! > Steve >
