From 7ebd56579f5e90861c39fdf46fa7d53446cfeccf Mon Sep 17 00:00:00 2001 From: Linus Nordberg Date: Wed, 18 May 2016 12:07:50 +0200 Subject: Read from and write to MKM when panic button is pressed. --- README.md | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 README.md (limited to 'README.md') diff --git a/README.md b/README.md new file mode 100644 index 0000000..2ccba7d --- /dev/null +++ b/README.md @@ -0,0 +1,33 @@ +Tamper detection for Atmel AVR ATtiny828 MCU on the Cryptech alpha +board, rev02. + + ************* + * P A N I C * + * button * + ************* + / + / + / + AVR ---- SPI mux ---- FPGA + | | + | ARM + MKM + +AVR -- Atmel MCU +FPGA -- FPGA +MKM -- Master Key Memory, 23K640 SRAM +SPI mux -- 2 x MC74AC244DW +ARM -- ARM CPU + +The MKM holds the master key for the device. + +The AVR, MKM and the mux are battery powered. + +The AVR and the FPGA are sharing access to the MKM through the mux, +with the AVR connected to the pins used for deciding who's in control +of the memory. The FPGA is in control by default. + +When the panic button is pressed, the AVR grabs the MKM and writes +zeros to it as quickly as possible. In idle mode, i.e. when the panic +button is not pressed, the AVR tries to consume as little power as +possible. -- cgit v1.2.3