Secure access to fluid cartridge memory

A method for secure communications between a printer and integrated fluid cartridge (100) comprising:

• connecting said integrated fluid cartridge (100) to said printer via an electrical interface (200), said integrated fluid cartridge (100) comprising a dispensing means and a memory module (150, 215);
• wherein said electrical interface (200) comprises a number of select lines (250) and a number of data lines (255), said number of select lines (250) and said number of data lines (255) being connected to both of said dispensing means and said memory module (150, 215);
• controlling said dispensing means via said number of select lines (250) and said number of data lines (255) such that fluid is dispensed from said integrated fluid cartridge (100);
• and
• controlling said memory module (150, 215) via said number of select lines (250) and said number of data lines (255) such that data can be written to and read from memory elements (325) contained in said memory module (150, 215).

A method for securing on-cartridge data comprising:

• connecting a printer to an integrated print cartridge (100) via an electrical interface (200), said integrated print cartridge (100) comprising a dispensing means and a memory module (150, 215) wherein said electrical interface (200) comprises number of select lines (250) and number of data lines (255), said number of select lines (250) and said number of data lines (255) being connected to both of said dispensing means and said memory module (150, 215);
• controlling said dispensing means via said number of select lines (250) and said number of data lines (255) such that ink is dispensed from said integrated printer cartridge (100);
• controlling said memory module (150, 215) via said number of select lines (250) and said number of data lines (255), said memory module (150, 215) containing a shift register (315, 320), said shift register (315, 320) being connected to said number of serial lines and said number of data lines (255), wherein said shift register (315, 320) comprises a plurality of stages, each of said stages corresponding to column or row of said memory array (310);
• accessing a memory element (150, 215) by asserting a logical signal over a first data line (255) of said number of data lines (255) and sequentially cycling said number of select lines (250) to advance said shift register (315, 320) through said stages, said logical signal being stored in said stages such that a row and a column corresponding to said memory element (150, 215) are set to an upper logical value;
• reading said memory element (150, 215) by passing a current through said memory element (150, 215) and reading a resulting analog voltage;
• wherein said reading said memory element is performed within a short time period, said short time period being substantially equal to a time that said shift registers (315, 320) maintain said row and said column at said upper logical value;
• and
• comparing said analog voltage with a reference voltage to produce a binary digit, said binary digit representing a logical value of said memory element (150, 215);
• wherein said data signals passed over said number of select lines (250) and said number of data lines (255) to control said dispensing means and said memory module (150, 215) are merged into a continuous data stream.