Interesting. I wonder how many motes are affected by this issue. Looks like this CC2420 problem should only only affect a subset of applications that use lower voltages than regular AA's can supply. Some components on the mote (i.e. flash) require voltages higher than 1.8V to operate. But if we can save 1.2 mA across the board even for higher voltages, it's definitely worth implementing.
Thanks for pointing this out, -David -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of harish prabhu Sent: Thursday, December 07, 2006 3:21 AM To: tinyos-help_list Subject: [Tinyos-help] CC2420 Errata Note 003,rev 0.3 : Setting RXCTRL1.RXBPF_LOCUR Hi All, One of the Chipcon errata notes suggests setting the RXCTRL1.RXBPF_LOCUR bit. This is a fix for a problem that occurs when the VDD pins are supplied with voltage less than 1.8 V. Importantly, it also notes that setting this bit will also reduce Rx current consumption by 1.2 mA ! I do not see the bit being set in the TOS 1.x code or in the TOS 2.x code (I checked the Telos related code). Isn't the 1.2mA current saving a good enough reason to set this bit ? Regards, Harish Chipcon's CC2420 Errata Note 003, rev 0.3 is partly copied below : ============================================== For CC2420 devices marked with lot codes ranging from WA8402.00 to WB8341.00 operation using VDD supply voltages below 1.8 V can lead to packet loss. This problem, which occurs mainly at low temperatures, is now fixed and operation down to 1.6 V is ensured for devices with lot codes succeeding WB8341.00. Description and reason for the problem ============================ When supplying the 1.8 V VDD supply pins (pins no. 1, 2, 3, 4, 10, 14, 15, 17, 18, 20, 26, 35, 37, 44, 48) with voltages below 1.8 V, oscillations in the receive filter has been observed for some devices. This phenomenon has mainly been observed at low operating temperatures, and will lead to degraded or non-functional signal reception. Applications using the internal regulator at room temperature or above are unlikely to encounter this issue. Suggested workaround ================= This issue is corrected in CC2420 with lot codes succeeding WB8341.00. In order for the fix to work properly, the following register setting must be used during receive mode: [RXCTRL1.RXBPF_LOCUR] = 1 This setting will reduce the RX current consumption by approximately 1.2 mA, and is compatible with previous versions of the CC2420. Chipcon's IEEE 802.15.4 MAC will support this setting from version 0.71. No workaround exists for CC2420 versions with lot codes between WA8402.00 and WB8341.00. Fix === Using CC2420 with lot codes succeeding WB8341.00, in conjunction with the suggested register setting, fixes the issue.
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