Thanks a lot for your reply. I am using Chipcon boards CC2420DBK from Texas Instruments (http://focus.ti.com/docs/toolsw/folders/print/cc2420dbk.htm)
My platform exports SPI on a 20-pin connector, so can I use it for arbitration or I should still use software arbitration. I saw at /tos/platforms/chips/cc2420/HplCC2420PinsC that for CC2420 communication, only the Slave Select Line is used from the HplAtm128SpiC and not MISO pin. Whereas my SPI interface (a 7-segment LED screen in this case) is only expecting a Clock and Data input from the Atm128. I saw the schematics of Micaz and it appears that the Atm128 and CC2420 connection does not use the SCK and MOSI/MISO connections which are provided on the 51-pin connector (PROG_MOSI, PROG_MISO, SPI_SCK). Does that mean that these connections are free to use without selecting between the radio chip and any other spi device, I mean it will not interfere with the radio communication, am I right???? Am I on the correct path? You said in your reply a following sentence: "You'll see that it connects HplCC2420SpiP's to Atm128SpiC; the latter provides the power lock to the former" Did you mean HplCC2420SpiC's instead of HplCC2420SpiP's??? This is what I have thought that I will do: I will need to have a HplLEDScreenC.nc which connects to Atm128SpiC and rest will be taken care of by the Atmegas's Hardware Abstraction layers. Secondly, in my application, I will need to call SpiPacket/SpiByte interface wired to HplLEDScreenC in the module. But then how will it work out that it needs to send this to the SPI device and not CC2420, will I need to use a different am id?? Regards, Varun Jain R&D Embedded Design Engineer Spiderbox Pty. Ltd. P: +617 3318 9509 F: +617 3318 9595 M: +61401 091 248 E: [EMAIL PROTECTED] W: http://www.spiderbox.com.au -----Original Message----- From: Philip Levis [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 05, 2008 2:04 AM To: Varun Jain Cc: [email protected] Subject: Re: SPI Bus arbitration on micaz On Aug 3, 2008, at 11:05 PM, Varun Jain wrote: > Hello Dr.Phil, > I was looking through the archives and I found that you have > discussed the topic about using multiple SPI devices. In the > following link you said that you might post some code for using > multiple SPI devices: > > http://mail.millennium.berkeley.edu/pipermail/tinyos-help/2008-April/032 819.html > > > Have you posted it somewhere?? I am trying to attach an LED screen > to the SPI interface of the atmel atmega128 processor. My platform > (Chipcons CC2420DBK) is very similar to Micaz and I have ported my > platform in TinyOS correctly and all the test applications are > working correctly. I am now building an application where I need to > display certain data to all the nodes in the network and collect > data to a BaseStation. So, for displaying I need to attach this > external LED/LCD screen. > > DOES anyone else has used SPI in micaz to interface some external > devices using arbitration. Will the following process work for this > task: > Toggle clock line > Set the output line > Send the data from master to slave > > Also I wanted to know that if we are using Dissemination to insert > data into the network every few seconds, then will it be alright to > use SPI to interface external devices as there might be a conflict > in accessing the SPI bus. The micaz does not export the SPI interface via the 51-pin connector: it is dedicated to the CC2420. The SPI to the at45db is just bit- banged GPIO. You therefore need to connect directly to the atm128 if you want to use the SPI. Take a look at the schematic. For software arbitration, look at platform/micaz/chips/cc2420/ HplCC2420SpiC.nc. You'll see that it connects HplCC2420SpiP's to Atm128SpiC; the latter provides the power lock to the former. So that's Atm128SpiC is the component you want to connect to. Phil _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
