One additional comment. On Mon, Sep 10, 2012 at 10:25 PM, Xiaohui Liu <[email protected]> wrote:
> Thank you for your prompt and helpful reply. CIL. > > On Mon, Sep 10, 2012 at 1:25 AM, Eric Decker <[email protected]> wrote: > >> >> >> On Sun, Sep 9, 2012 at 9:39 PM, Xiaohui Liu <[email protected]> wrote: >> >>> Hello all, >>> >>> I have a few things uncertain about USART on TelosB. >>> >>> 1) This may be naive, but I'm really curious why USART is needed in the >>> first place. Why can't the CPU talk to, say, CC2420 directly since they are >>> wired >>> together<http://webs.cs.berkeley.edu/tos/hardware/telos/telos-revb-2004-09-27.pdf> >>> ? >>> >> >> Huh? Well take a look at the 1611 data sheet. The USART hardware >> provides various functions but not at the same time. The CPU talks to the >> CC2420 through the USART as SPI. >> >> Read the TI data sheet and the user manual. And look at the telosb >> schematic. >> > From page 6 of the > datasheet<http://www.ti.com/lit/ds/symlink/msp430f1611.pdf> showing functional > block diagram of MSP430F16x, P3 and USART0 seem to be separated. But from > the > schematic<http://webs.cs.berkeley.edu/tos/hardware/telos/telos-revb-2004-09-27.pdf>, > P3.1 is used as SIMO signal when USART0 is configured as SPI mode. Is this > because in TelosB, USART0's SIMO pin is physically wired to P3.1? > >> >> >>> >>> 2) What components/devices/peripherals are communicating with CPU via >>> USART? Via which one (USART0 or USART1) and in which mode (UART, SPI, or >>> I2C)? >>> >> >> look at the schematic. >> >> > USART0 is connected to CC2420 in SPI or I2C mode. Its UART mode is not > used. > USART1 is connected to USB in UART mode. Its SPI mode is not used. > >> >>> 3) Can USART0 and USART1 be used in parallel? >>> >> >> yes. look at the data sheet. >> >> > *So SPI can be accessed even when UART is transmitting or receiving since they are dealt with independent USART modules?* > For instance, can a strobe be sent to CC2420 using USART0 while the RSSI >>> register on CC2420 is being read using USART1? >>> >> >> huh again. I beleive a strobe is a message sent to the CC2420 but may >> also use a directly wired pin. >> >> The cc2420 is wired via only one set of hardware so your suggestion is >> non-sensical. >> >> >>> >>> Your explanation will be highly appreciated. >>> >>> -Xiaohui Liu >>> >>> >>> _______________________________________________ >>> Tinyos-help mailing list >>> [email protected] >>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >>> >> >> >> >> -- >> Eric B. Decker >> Senior (over 50 :-) Researcher >> >> >> > > > -- > -Xiaohui Liu > -- -Xiaohui Liu
_______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
