Datasheet

3.3.2 Particulars from the AT45DB011 datasheet

The Adesto Technologies AT45DB011 1Mbit DataFlash chip [20] found in original Davis

data loggers contains the storage space for logging weather observations from the con-

sole.

The AT45DB011 DataFlash chip is well documented and it even supports a limited

instruction set. The instruction set is typically used to store and retrieve data and to

carry our related ”housekeeping functions”.

Each DataFlash chip comes with a unique, factory-programmed 64-byte device iden-

tiﬁer which cannot be modiﬁed. The chip also has what is known as a programmable

64-byte security register. The security register can be programmed once — once pro-

grammed, it cannot be changed. The original Davis data loggers all come with pro-

grammed security registers, in which each of the 64 bytes has been calculated during

the ”burn in” stage of production.

It is noteworthy that even non-green dot data loggers come with programmed secu-

rity registers in the AT45DB011 DataFlash chips. The values in the security registers of

the non-green dot units are obviously calculated in a way which will not ensure valida-

tion of the data loggers when used with green dot consoles.

For simplicity, further references to the security register will regard the device iden-

tiﬁer (64 bytes) and the actual security register (64 bytes) as one single 128-byte entity.

OpCode Req’d Description

0xD7 Yes Return chip status. Returning 0x8C will do the trick.

0x77 Yes Return security register, 128 bytes.

0x9F No Return manufacturer ID and data density. Values 0x1F and

0x22 identify the AT45DB011 DataFlash chip.

Table 1: Relevant opcodes for the AT45DB011 DataFlash chip [20]. The ”required” ﬁeld indicates which

opcodes are required for data logger authentication.

Although not required to authenticate an original Davis data logger, the 0x9F op-

code returns 0x1F (binary 00011111) which identiﬁes Adesto Technologies as manu-

facturer and 0x22 (binary 00100010) which indicates what data density is found on

the (1 Mbit) DataFlash chip.

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