RELEASE
Revision B1
©Serious Integrated, Inc.
34
CRYPTOGRAPHIC/AUTHENTICATION DEVICE
The SIM535 features an
Atmel ATSHA204
Cryptographic/Authentication device with built-in Random Number Generator
(RNG) and EEPROM. The ATSHA204 is an I2C device on the SIM’s main I2C control bus.
Within this device is 4Kb (512 byte) EEPROM for storing security keys and/or parameter data. If the cryptographic and
authentication features of the ATSHA204 are not used, the device can be used simply as a user EEPROM.
The 512 bit OTP area within the 4.5Kb EEPROM is pre-programmed by
Serious
and is unavailable for other uses.
Modifying or writing to this area
will void your warranty with
Serious
and render the module unusable.
See the
I2C Device Summary
for the complete table of I2C device addresses.
Consult the
Atmel ATSHA204 Data Sheet
for programming and hardware information of the ATSHA204 device.
PCB TEMPERATURE SENSING
Some SIM535 variants also contain an
On Semiconductor NCT75
or equivalent for measuring the system/PCB
temperature. This sensor is excellent for keeping track of general system temperature, but is not an ambient air
temperature sensor: accurate air temperature sensors require separation from the circuit board in order to isolate the
sensor from heating sources on the board – especially the heating of the LCD backlight. As a result, the PCB
Temperature Sensor will typically read a few degrees above that of the ambient temperature. The high level
specifications for this device are:
Parameter
Value
Accuracy
Maximum Sample Rate
(12 bit)
50mS
Maximum Resolution
12 bit
Typical @ 25°C
±0.5°C
Worst Case @ 0°C to +70°C
±1.0°C
Supply Current
Typical
440uA
Max
800uA
Shutdown Typical
3uA
The temperature sensor is an I2C device on the SIM’s main I2C control bus.
See the
I2C Device Summary
for the complete table of I2C device addresses.
The temperature sensor can be programmed to interrupt the CPU when a temperature threshold has been exceeded.
The
ALERT#
signal is connected to an MCU GPIO/Interrupt signal.
See the
Interrupt Summary
for the complete table of external peripheral interrupts.
See
the NCT75 datasheet
for more hardware specifications and programming information.
GUIs developed in SHIPTide can access the PCB Temperature Sensor’s value at runtime.
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