This is also a problem I want to check. I have designed a TDMA mechanism there, And I ignored the return value of call STXON.strobe(); It seems there is no big problem. There seems no detailed info about that in the CC2420 datasheet.
Anybody who knows it better? Jinzhi Liu From: [email protected] [mailto:[email protected]] On Behalf Of Xiaohui Liu Sent: Wednesday, May 02, 2012 4:49 AM To: Tinyos-Help Subject: [Tinyos-help] will packets with CCA disabled backoff if channel is busy? Hi, The following snippet is from CC2420TransmitP: call CSN.clr(); status = m_cca ? call STXONCCA.strobe() : call STXON.strobe(); if ( !( status & CC2420_STATUS_TX_ACTIVE ) ) { status = call SNOP.strobe(); if ( status & CC2420_STATUS_TX_ACTIVE ) { congestion = FALSE; } } m_state = congestion ? S_SAMPLE_CCA : S_SFD; call CSN.set(); } if ( congestion ) { totalCcaChecks = 0; releaseSpiResource(); congestionBackoff(); } else { call BackoffTimer.start(CC2420_ABORT_PERIOD); } I understand call STXONCCA.strobe() will not send the packet if channel is busy. Will call STXON.strobe() always return CC2420_STATUS_TX_ACTIVE and send the packet regardless of the channel state? If no, under what condition can this happen? Thanks for your attention. -- -Xiaohui Liu
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