Flash Hardware Write Protection - moteiv Telos User Manual

Flash Hardware Write Protection

The flash includes hardware write protection functionality. The write protection exists on a
sector basis as shown in Figure 18. The hardware write protection pin (Pin 3 of the M25P80
shown in Figure 16) only disables write protection when the module is powered by the USB port.
When connected to USB, the status register must be updated by removing the write protect and
block protect bits in Figure 17. The write protected segments may only be changed after the
module connected to USB and the write protect bit is cleared.
Telos ships with sector 15 (the upper sixteenth sector) write protected and the SRWD bit set. In
sector 15 is the "Golden Image" and factor metadata. The "Golden Image" is a factory program
image that includes network reprogramming so that Telos may always return to a known good
state, even if loaded with a malfunctioning program image. When Telos is connected to the
USB, the "Golden Image" may be changed. See the TinyOS Deluge documentation in
tinyos-1.x/docs of the TinyOS distribution included with Telos.
Status Register Content
BP2 Bit BP1 Bit
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
NOTE: When programming data to write protected segments of external flash, do not
disconnect the module before the programming is completely. If the module is
disconnected from the USB, the write may be interrupted or the status register may not be
updated to reflect the new write protection settings.
Moteiv Corporation
b7
SRWD 0 0
Status Register
Write Protect
Figure 17 : ST M25P80 Status Register contents (from ST).
BP0 Bit Protected Area
0 None
1 Upper sixteenth (15)
0 Upper eighth (14-15)
1 Upper quarter (12-15)
0 Upper half (8-15)
1 All sectors (0-15)
0 All sectors (0-15)
1 All sectors (0-15)
Figure 18 : Write protection settings for the ST M25P80 flash.
Telos Rev B modules are shipped with the gray setting (001).
Telos (Rev B) : PRELIMINARY Datasheet (12/5/2004)
Rev B (Low Power Wireless Sensor Module)
BP2 BP1 BP0 WEL
Block Protect Bits
Write Enable Latch Bit
Write In Progress Bit
Memory Content (Sectors)
Unprotected Area
All sectors (0-15)
Lower fifteen-sixteenths (0-14)
Lower seven-eighths (0-13)
Lower three-quarters (0-11)
Lower half (0-7)
None
None
None
Telos
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WIP
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