[sim-wg] Re: Incorporation of Mica2 simulation

[Philip Levis]

On Jun 9, 2007, at 9:16 AM, Venkatesh S. wrote:

> Hi phil,
>    The first update was to just compile for mica2 simulation  
> without inclusion of the CC1000 radio simulation.
> I have updated the CVS for CC1000 Radio simulation.
>
> CORE logic:
>    1) ADC0 sampling:  The MAC layer samples the ADC0 port for  
> receiveing RSSI and decides whether the medium is busy or free.  To  
> do this, the HplAtm128AdcP was modified to incorporate the same.   
> Here, the input to the simulator will be the rssi-log for Mica2  
> platform.  The log is found in apps/tests/TestAM/rssi-log- 
> mica2.txt.  Once this is fed, at the ADC0, we get a simulated RSSI  
> value based on CPM, which is converted back to digital value and  
> signal the same to the MAC layer.
>    2) Once the MAC layer decides that the medium is free, it begins  
> its transmmission. Byte by Byte transmission is done in  
> HplCC100SpiP which is simulated as events.  For every byte  
> transmission, based on the neighbor Radio state, a spiReadByte  
> event in allocated.
>
> Problems Facing:
>    1)  If the event time is just sim_time(), the service of the  
> write events takes first without subsequent events of the read  
> events for the other nodes. So, I changed to the event time to  
> trigger at sim_time()+10002.  Is that correct?
I don't understand. It seems like if one node writes a byte to  
transmit for the SPI, then other nodes should have receive events at  
approximately (8 * (sim_ticks_per_second/radio_bits_per_second)).  
They should not get a receive event until the last bit has been  
transmitted, rather than when the first bit starts transmitting.

>    2)  I am using the standard application for testing(TestAM).   
> For Broadcast, since there is no ack, nodes transmit.  Reception is  
> also working fine.  If the application is simulated for 10 seconds  
> it has to have 10 packets Tx and Rx, but it is only doing 2 packets  
> Rx and Tx.  I couldn't figure out where the actual bug is. I badly  
> need help in this.
If you fix part 1) above, I might be able to take a look later this  
week.


Phil