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Tattletale Installation and Operation Manual
ANSI-C
Section 6 - Hardware and Interface Specifications
development: CS0, CS1, CS2 and CS10. Unlike the QSPI peripheral chip selects, the
SIM chip selects cannot be MUXed.
BDM (Background Debug Mode)
The 68332 features a background debug mode which, in the Model 8, is used to
institute emergency procedures when the flash EEPROM (program source) is lost or
the 68332 hangs up. Under such conditions, the watchdog will timeout and send the
68332 into a reset loop. The 332's reset line is connected to the RTCC line on the PIC
part. The PIC can be programmed to count resets and, after a predetermined number of
consecutive resets, initiate BDM by pulling DSCLK low.
PIC 16C64
The 16C64 is an EPROM based 8 bit CMOS microcontroller. One of the many
features of this microcontroller is low current drain. The Model 8 is designed to utilize
the PIC to survive extended periods of near inactivity while monitoring for the start of
an event.
In the low power mode, the PIC takes full control of the Model 8 while the 68332 is
stopped. While the 68332 is stopped, the PIC can be programmed to wakeup at fixed
intervals and check the sensor inputs for measurements which would indicate the need
of the 332. Alternatively, the PIC can be tipped off by an interrupt to wake the 332.
The 16C64 includes a Real Time Clock/Counter (RTCC) module. The RTCC features
an 8-bit timer/counter, read/write, 8 bit software programmable prescaler, internal or
external clock select, interrupt on overflow from FFh to 00h and edge select for
external clock. In the Model 8, the RTCC is used to monitor the 332 through the reset
line. RTCC can thus be configured to start BDM emergency procedures on the 332.
Consult the Microchip data sheet for further details (data sheet not provided by Onset).
Oscillator
The Model 8 uses a Harris HA7210; low power crystal oscillator with a Statek 40 KHz
tuning fork quartz crystal. The crystal has an initial accuracy of ± 0.003% at 25 °C. ,
and will operate from –40°C to +85°C with a stability of about –0.035 ppm/°C2. This
crystal also has excellent aging characteristics; however, like any crystal it will change
over time. Refer to Figure 6-9 for the oscillator error curve.
D-3285-C
Onset Computer Corporation - Model 8 with C
Page 6-21